TK 

4161 
CM 

1919 


General  Lighting 
Safety  Orders 


UC-NRLF 


Issued  by  the 

Industrial  Accident  Commission 

of  the 
State  of  California 


525  MARKET  STREET,  SAN  FRANCISCO 


Effective  December  1,  1919 


CALIFORNIA  STATE  PRINTING  OJTIC1 
SACRAMENTO 

1919 


General  Lighting 
Safety  Orders 


Issued  by  the 

Industrial  Accident  Commission 

of  the 
State  of  California    «       « 


525  MARKET  STREET,  SAN  FRANCISCO 


Effective  December  1,  1919 


CALIFORNIA  STATE  PRINTING  OFFICE 
SACRAMENTO 

1919 


(7800 


INDUSTRIAL   ACCIDENT  COMMISSION 
OF   THE    STATE    OF  CALIFORNIA 


525  Market  Street,  San  Francisco 

423  Union  League  Building,  Los  Angeles 


,    Chairman. 


A.  H.  NAFTZGER, 

Commissioners. 


H.  M.  WOLFLIN, 

Superintendent  of  Safety. 


SUMMARY  OF  THE  SAFETY  PROVISIONS 

of  the 
Workmen's  Compensation,   Insurance  and  Safety  Act. 

Being   Chapter  176  of  the   Laws  of  1913  as  Amended   by  Chapter  607  of  the 
Laws  of  1915,  and  Chapter  586  of  the  Laws  of  1917. 

Sections  33  to  54,  inclusive,  of  the  Workmen's  Compensation,  Insur- 
ance and  Safety  Act  give  the  Industrial  Accident  Commission  power  to 
make  and  enforce  safety  orders,  rules  and  regulations,  to  prescribe  safety 
devices,  and  to  fix  safety  standards.  It  also  empowers  the  Commission 
to  appoint  advisers  who  shall,  without  compensation,  assist  the  Com- 
mission in  establishing  standards  of  safety.  The  Commission  may  adopt 
and  incorporate  in  its  general  orders  such  safety  recommendations  as  it 
may  receive  from  such  advisers. 

The  Commission,  carrying  out  its  plan  of  obtaining  the 
best  practical  ideas  to  incorporate  in  its  Safety  Orders,  asked 
various  interests  to  serve  on  a  committee  to  draft  Tentative 
General  Lighting  Safety  Orders. 

COMMITTEE  ON  GENERAL  LIGHTING  SAFETY  OEDEBS. 

ROMAINE  W.  MYERS  (chairman),  consulting  engineer  (electrical  and 
illuminating),  representing  the  National  Council  of  Defense,  Divis- 
ional Committee  on  Lighting. 

L.  E.  VOTER  (vice  chairman),  illuminating  engineer,  General  Electric 
Company,  representing  the  Association  of  Electrical  Manufacturers 
and  the  Lighting  Fixture  Association. 

W.  W.  HANSCOM,  electrical  and  mechanical  engineer,  representing  the 
National  Electric  Light  Association,  Pacific  Coast  Section. 

SMITH  O'BRIEN,  architect,  representing  the  American  Institute  of 
Architects. 

R.  H.  FENKHAUSEN,  electrical  engineer,  Bethlehem  Shipbuilding  Corpo- 
ration, Union  Plant,  representing  the  American  Institute  of  Electrical 
Engineers. 

DANIEL  C.  MURPHY,  president  California  State  Federation  of  Labor. 

PAUL  SCHARREXBERG,  secretary-treasurer  California  State  Federation 
of  Labor. 

R.  S.  PRUSSIA,  illuminating  engineer,  Westinghouse  Lamp  Company, 
representing  the  Association  of  Electrical  Manufacturers. 

MILES  F.  STEEL,  Benjamin  Electric  Manufacturing  Company,  repre- 
senting the  Association  of  Electrical  Manufacturers. 

S.  J.  LISBERGER,  Engineer,  San  Francisco  District,  Pacific  Gas  and 
Electric  Company,  representing  the  Pacific  Coast  Gas  Association. 

CHAS.  M.  MASSON,  illuminating  engineer,  Southern  California  Edison 
Company,  representing  the  Illuminating  Engineering  Society. 

CONSTANT  MEESE,  Meese  &  Gottfried  Company,  representing  the  San 
Francisco  Chamber  of  Commerce. 

F.  DOHRMANN,  JR.,  Nathan-Dohrmann  Company,  representing  the  San 
Francisco  Chamber  of  Commerce. 

HARRY  GORMAN,  field  agent,  representing  the  Bureau  of  Labor  Statistics. 

H.  B.  WOODILL,  president  Woodill  &  Hulse  Electric  C9mpany,  Inc., 
representing  the  Merchants  and  Manufacturers  Association  of  Los 
Angeles. 

W.  A.  CHOWEN,  manager  California  Inspection  Rating  Bureau,  repre- 
senting the  Casualty  Underwriters  Board  of  California. 

D.  AYRE,  superintendent  inspection  department,  California  Inspection 
Rating  Bureau,  representing  the  Casualty  Underwriters  Board  of 
California. 

HAROLD  MESTRE,  representing  the  Industrial  Welfare  Commission. 

ROBT.   L.   ELTRINGHAM,   electrical   engineer,   representing   the   Indus- 
trial Accident  Commission. 

JOHN  R.  BROWNELL  (secretary),  superintendent  of  safety,  Industrial 
Accident  Commission. 

Acknowledgment  is  made  of  the  assistance  rendered  by  the  Illuminating 
Engineering  Society  in  the  preparation  of  these  General  Lighting  Safety 
Orders,  and  for  the  use  of  the  various  cuts  which  they  kindly  loaned. 


M48977 


GENERAL  LIGHTING  SAFETY  ORDERS. 
Order  1500.     Definitions. 

(a)  Candle   (or  candlepower)   means  the  unit  of  luminous 
intensity  maintained  by  the  national  laboratories  of  the  United 
States,  France  and  Great  Britain. 

(b)  Lumen  means  the  unit  of  luminous  flux,  and  is  the 
quantity  of  light  necessary  to  produce  an  average  intensity  of 
illumination  of  one  foot-candle  over  an  area  of  one  square  foot. 

(c)  Foot-candle  means  the  unit  of  illumination  equal  to  one 
lumen  per  square  foot.     It  is  the  lighting  effect  produced  upon 
an  object  by  a  lamp  of  one  candlepower  at  a  distance  of  one 
foot. 

(d)  Photometer  means  a  standardized  instrument  suitable 
for  making  illumination  measurements. 

(e)  Lamp  means  that  part  of  the  lighting  equipment  from 
which  the  light  originates. 

(/)  Local  lamps  (or  lighting)  means  lighting  units  located 
close  to  the  work,  and  intended  to  illuminate  only  a  limited 
area  about  the  work. 

(g)  Overhead  lamps  (or  lighting)  means  lighting  units 
installed  above  ordinary  head-level  to  secure  a  general  illumi- 
nation over  a  considerable  area. 

(h)  Brightness  means  the  intensity  of  light  per  unit  area 
emitted  from,  or  reflected  by,  a  body ;  and  in  these  Orders 
is  expressed  in  candlepower  per  square  inch. 

(i)  Glare  means  any  brightness  within  the  field  of  vision  of 
such  a  character  as  to  cause  discomfort,  annoyance,  interfer- 
ence with  vision,  or  eye  fatigue. 

(j)  Eyestrain  means  a  physiological  condition  of  the  eye 
resulting  in  discomfort,  poor  vision,  or  fatigue. 

(k)  Shaded  means  that  the  lamp  is  equipped  with  a  reflector, 
shade,  enclosing  globe,  or  other  accessory  for  reducing  the 
brightness  in  certain  directions,  or  otherwise  altering  or  chang- 
ing the  distribution  of  light  from  the  lamp. 

(I)  Illumination  means  the  quantity  of  light  received  upon 
a  surface ;  it  is  measured  in  foot-candles  or  in  lumens  per  square 
foot  of  area. 

(m)  Intensity  of  illumination  means  the  quantity  of  light 
received  upon  a  surface,  expressed  in  foot-candles  or  in  lumens 
per  square  foot  of  area. 


GENERAL   LIGHTING   SAFETY   ORDERS.  5 

(n)  Foot-candles  at  the  work  means  the  intensity  of  illumi- 
nation on  the  object  upon  which  work  is  being  performed. 

(0)  Foot-candles  at  floor-level  means  the  intensity  of  illumi- 
nation on  the  floor  of  the  space  specified. 

Order  1501.     General  Requirements. 

(a)  Working  or  traversed  spaces  in  buildings  or  grounds 
of  places  of  employment  shall  be  supplied  during  the  time  of 
use,  with  either  natural  or  artificial  light  in  accordance  with 
the  following  Orders  (1502-1509). 

Order  1502.     Natural  Lighting. 

(a)  Windows,  skylights  or  other  roof-lighting  construction 
of  buildings  shall  be  arranged  with  the  glass  area  so  appor- 
tioned that  at  the  darkest  part  of  any  working  space,  when 
normal  exterior  daylight  conditions  obtain  (sky  brightness  of 
1.50  candlepower  per  square  inch)  there  will  be  available  a 
minimum  intensity  equal  to  twice  that  of  Order  1503,  other- 
wise artificial  light  of  intensities  specified  in  Order  1503  shall 
be  provided. 

(&)  Awnings,  shades,  diffusive  or  refractive  window  glass 
shall  be  used  for  the  purpose  of  improving  daylight  conditions 
or  for  the  avoidance  of  eyestrain  wherever  the  location  of  the 
work  is  such  that  the  worker  must  face  large  window  areas 
through  which  excessively  bright  light  may  at  times  enter  the 
building. 

NOTE. — The  intensity  requirements  for  adequate  day  lighting  are  much 
higher  than  those  for  adequate  night  lighting,  because  in  general  under 
daylight  conditions  the  light  reaching  the  eye  from  all  surroundings  in  the 
field  of  vision  is  much  brighter  than  at  night,  and  hence  a  correspondingly 
more  intense  light  must  fall  on  the  object  viewed. 

Order  1503.     Artificial  Light. 

(a)  When  the  natural  light  is  less  than  twice  the  minimum 
permissible  intensities  of  illumination  set  forth  in  the  following 
table,  artificial  light  shall  be  supplied  and  maintained  in 
accordance  with  the  table. 

NOTE. — See  Appendix  for  intensities  recommended  for  best  working 
conditions. 

Foot-candles  at  the  floor  level 

1.  Roadways  and  yard  thoroughfares 0.02 

2.  Storage  spaces,  stairs,  stairways,  halls,  hallways, 

passageways,    aisles,    exits    and    elevator    en- 
trances        0.25 

3.  Water-closet   compartments,   toilet   rooms,   wash- 

rooms, dressing  rooms  and  elevator  cars 0.50 


b  GENERAL   LIGHTING   SAFETY   ORDERS. 

Foot-candles  at  the  work 

4.  Work  not  requiring  discrimination  of  detail,  such 

as  handling  material  of  a  coarse  nature,  and 
performing  operations  not  requiring  close 
visual  application 0.50 

5.  Eough  manufacturing  requiring  discrimination  of 

detail,  such  as  rough  machining,  rough  assem- 
bling, rough  bench  work,  also  work  in  base- 
ments of  mercantile  establishments  requiring 
discrimination  of  detail 1.00 

6.  Rough  manufacturing  requiring  closer   discrim- 

ination of  detail,  such  as  machining,  assembly 
and  bench  work,  also  work  in  basements  of 
mercantile  establishments  requiring  closer  dis- 
crimination of  detail,  intermediate  between 
5  and  7 2.00 

7.  Fine  manufacturing,  such  as  fine  lathe  work,  pat- 

tern and  tool  making,  also  office  work,  such  as 
accounting  and  typewriting 3.00 

8.  Special  cases  of  fine  work,  such  as  watchmaking, 

engraving  and  drafting 5.00 

9.  Processes  otherwise  safeguarded  in  which  light  is 

detrimental    i 0.00 

NOTE. — Some  exceptions  to  the  intensity  rule : 
(a)   There  are  some  operations  that  are  performed   in  compar- 
ative   darkness,    as    for    example,    photographic    processes    in    the 
dark    room. 

(6)  There  are  some  operations  that  are  best  observed  by  their 
own  light,  as  in  parts  of  the  process  of  working  glass. 

(c)  Some^  operations  are  best  observed  by  the  "silhouette" 
method  of  lighting  in  which  the  work  is  seen  against  a  lighted 
background  in  a  comparatively  dark  room,  as  in  some  processes  of 
working  with  dark  threads  and  lamp  filaments. 

In  all  such  cases  in  which  work  is  of  necessity  carried  on  in 
comparative  darkness,  special  precautions  should  be  taken  to 
properly  safeguard  the  workmen. 

Order  1504.     Measurements. 

(a)  For  the  purpose  of  light  measurements,  a  standardized 
photometer,  certified  by  the  Industrial  Accident  Commission  of 
the  State  of  California,  shall  be  used,  and  such  measurements 
shall  be  made  at  the  locations  specified  in  the  table. 

Order  1505.    Shading  of  Lamps  for  Overhead  Lighting. 

(a)  Lamps  suspended  at  elevations  above  eye  level  less  than 
one-quarter  their  distance  from  any  positions  at  which  work 
is  performed,  or  where  places  are  traversed,  must  be  shaded  in 
such  a  manner  that  the  intensity  of  the  brightest  one-quarter 
square  inch  of  visible  light  source  shall  not  exceed  seventy-five 
candlepower  per  square  inch. 


GENERAL   LIGHTING    SAFETY   ORDERS.  7 

NOTE. — The  following  diagram  illustrates  the  application  of  the  above 
rule,  the  distances  being  explanatory  and  representing  the  ratio  between 
the  height  of  the  lamp  above  the  eye  level  and  its  horizontal  distance 
from  the  eye. 

L  /nz  -7 


L  a/npj  be/o  w  the  l/rr?/  there  shown  ft  02  td/s  fa/rt 

must"  be  3O  -shaded  thaf  the.  Casrd/e 

Power  o  fthe  brtghfes  t£  3<p  s/f.  of 

the  L  tfhf'  Jot/rce  sho//fro  /"  e  /r  c  eed  work  i  '5  pc-  r- 

75CS?  per  jy.  /sr.  forsn  e  d 

^~-  ~~^~  *TT  Limited  height 


Exception.  Lamps  suspended  at  elevations  greater  than 
twenty  feet  above  the  floor  are  not  subject  to  this  requirement. 

NOTE  1.  —  Glare  from  lamps  or  unduly  bright  surfaces  produces  eye- 
strain  and  increases  the  accident  hazard.  The  brightness  limit  specified 
in  this  Order  is  an  absolute  maximum.  \7ery  much  lower  brightness 
limits  are  necessary  in  many  interiors  illuminated  by  overhead  lamps,  if 
the  illumination  is  to  be  satisfactory.  In  some  cases  the  maximum 
brightness  should  not  exceed  that  of  the  sky  (two  to  three  candlepower 
per  square  inch). 

NOTE  2.  —  Where  the  principal  work  is  done  on  polished  surfaces,  such 
as  polished  metal,  celluloid,  varnished  wood,  etc.,  it  is  desirable  to  limit 
the  brightness  of  the  lamps  in  all  downward  directions  to  the  amount 
specified  in  this  Order. 

NOTE  3.  —  For  method  of  measuring  brightness,  see  Appendix,  para- 
graph 86. 

Order  1506.     Shading  of  Lamps  for  Local  Lighting. 

(a)  Lamps  for  local  lighting  must  be  shaded  in  such  a 
manner  that  the  intensity  of  the  brightest  square  inch  pre- 
sented to  view  from  any  position  at  which  work  is  performed, 
shall  not  exceed  three  candlepower. 

NOTE.  —  In  the  case  of  lamps  used  for  local  lighting,  at  or  near  eye 
level,  the  limits  of  permissible  brightness  are  much  lower  than  for  lamps 
used  for  overhead  lighting,  because  the  eyes  are  more  sensitive  to  strong 
light  received  from  below,  and  because  such  light  sources  are  more 
constantly  in  the  field  of  view. 

Order  1507.    Distribution  of  Light  on  the  Work. 

(a)  The  reflectors  or  other  accessories,  mounting  heights  and 
spacings  employed  with  lamps  shall  be  such  as  to  secure  a 
reasonably  uniform  distribution  of  illumination,  avoiding 


8  GENERAL   LIGHTING    SAFETY    ORDERS. 

objectionable  shadows  and  sharp  contrasts  of  brightness.  If 
local  lighting  is  used,  there  shall  be  employed  in  addition  a 
moderate  intensity  of  overhead  lighting,  with  a  minimum  of 
not  less  than  one-fourth  (J)  foot-candle. 

Exception.  "Where  the  light  from  the  local  lamps  falls 
principally  upon  surfaces  which  are  white  or  nearly  so,  and 
the  ceilings  and  walls  of  the  rooms  are  light,  there  is  often  a 
sufficient  general  illumination  received  indirectly  by  reflection 
to  obviate  the  necessity  of  additional  overhead  lighting. 

NOTE.  —  When  local  lighting  is  used  as  the  sole  source  of  illumination 
of  an  interior,  the  field  of  illumination  from  each  lamp  is  in  contrast  to 
the  surrounding  darkness,  thereby  causing  eyestrain  and  increasing  the 
accident  hazard. 

Order  1508.     Emergency  Lighting. 

(a)  Emergency  lights  shall  be  provided  in  all  workspace 
aisles,  stairways,  passageways,  exits,  outside  landings  of  fire 
escapes  and  other  structures,  used  as  regular  or  emergency 
means  of  egress.  These  emergency  lights  are  to  provide  for 
adequate  illumination  when,  through  accident  or  other  cause, 
the  regular  lighting  is  extinguished. 

NOTE  1.  —  It  is  the  intention  of  this  Order  to  guard  against  accident 
due  to  the  failure  of  the  regular  lighting  system,  by  providing  sufficient 
illumination  to  enable  the  occupants  to  : 

(a)   Avoid   contact  with   moving   machinery   and   other   danger   points 


until  the  regular  lighting  is  again  placed  in  operation. 

(6)   To    vacate    the    building    safely    a 
necessary  because  of  fire  or  other  causes. 


. 
(6)   To    vacate    the    building    safely    and    expeditiously    when    this    is 


NOTE  2.  —  Emergency  lighting  may  be  installed  in  various  ways.  The 
method  to  be  employed  depends  upon  the  size  of  the  premises,  the  extent 
of  the  hazards  of  employment,  and  the  means  available  for  supplying 
such  emergency  lighting. 

(&)  Emergency  lighting  systems,  including  all  supply  and 
branch  lines,  their  runways,  raceways  and  supports,  shall  be 
entirely  independent  of  the  regular  lighting  system,  and  shall 
be  lighted  concurrently  with  the  regular  lighting  system  and 
remain  lighted  throughout  the  period  of  the  day  during  which 
artificial  light  is  required  or  used. 

(c)  Emergency  lighting  shall  have  a  minimum  intensity  of 
one-fourth  (J)  foot-candle.     The  emergency  illumination  shall 
not  exceed  fifty  (50)  per  cent  of  the  distributed  illumination. 

(d)  Emergency  lighting  systems  shall  be  supplied  from  a 
source  independent  of  the  regular  lighting  system  in  theaters, 
public  meeting  halls,  moving  picture  exhibition  places,  hospitals, 
schools,  and  any  other  place  where  the  nature  of  the  hazard  is 
such  as  to  require  it,  except  where  an  exemption  is  granted  by 


GENERAL   LIGHTING   SAFETY   ORDERS. 

the  Industrial  Accident  Commission.  This  source  of  supply 
and  controlling  equipment  shall  be  such  as  to  insure  the  reliable 
operation  of  the  emergency  lighting  system  when,  through  acci- 
dent or  other  cause,  the  regular  lighting  system  is  extinguished. 
Where  a  separate  source  of  supply  can  not  be  obtained  for  the 
emergency  lighting,  the  feed  for  emergency  lighting  must  be 
taken  from  a  point  on  the  street  side  of  the  service  equipment. 
AY  here  source  of  supply  for  the  regular  lighting  system  is  an 
isolated  plant  within  the  premises,  an  auxiliary  lighting  system 
of  sufficient  capacity  to  supply  all  emergency  lighting  must  be 
installed  from  some  other  source,  or  suitable  storage  battery; 
or  separate  generating  unit  may  be  considered  the  equivalent 
of  such  service. 

Order  1509.     Switching  and  Control  Apparatus. 

(a)  Switches  or  other  controlling  apparatus  shall  be  so 
installed  that  pilot  or  night  lights  may  be  controlled  from  a 
point  at  the  main  entrance,  and/or  other  easily  accessible  points. 
Pilot  or  night  lights  may  be  a  part  of  the  emergency  lighting 
system. 

(&)  All  switching  and  control  apparatus  on  emergency, 
pilot  and  night  lights  shall  be  plainly  labeled  for  identification. 

NOTE. — The  purpose  of  this  Order  is  to  make  it  possible  for  the  night 
watchman  or  other  qualified  persons  to  turn  on  enough  lamps,  when 
entering  any  portion  of  the  premises  at  night,  to  enable  them  to  safely 
see  their  way  around  without  the  need  of  a  lantern  or  flashlight. 


>-47f 


10  GENERAL   LIGHTING   SAFETY   ORDERS. 


APPENDIX. 

GENERAL  INFORMATION   AND  SUGGESTIONS. 

1.  The  foregoing  orders  give  in  the  briefest  possible  form  the 
minimum  requirements  of  lighting  in  factories,  mills  and  other 
work  places   to   insure   reasonable   safety  to   workmen   from 
accident  and  injurious  eyestrain.     General  information  with 
detailed  discussion  of  the  methods  of  applying  the  orders  and 
of  obtaining  adequate  illumination  to  insure  efficient  production 
are 'presented  in  this  Appendix. 

2.  When  adequate  and  satisfactory  illumination  is  substi- 
tuted for  the  all  too  prevalent  poor  illumination  in  factories, 
mills  and  other  work  places,  the  results  obtained  are  mutually 
beneficial  to  the  employees,  the  employers,  and  the  country  as 
a  whole.     Under  proper  illumination  conditions,   the  health, 
contentedness,  safety  and  skill  of  the  employees  are  maintained 
at  a  high  standard,  the  output  is  increased  in  quantity  and 
improved  in  quality,  while  there  is  a  proportional  reduction  in 
the  cost  of  each  unit  of  finished  products  when  it  reaches  the 
public. 

3.  While  it  is   desirable  to  have  adequate  light  over  the 
working  areas,  it  is  absolutely  essential  for  the  proper  results 
to  eliminate  or  minimize  the  light  which  otherwise  would  pass 
directly  from  the  lamps  to  the  eyes  of  the  workers ;  that  is,  one 
must  avoid  glare  which  is  not  only  fatiguing  to  the  eye  but 
also  conducive  to  the  incorrect  estimation  of  sizes  and  locations 
of  objects  in  the  field  of  view. 

4.  Glare  effects  may  be  caused  not  only  by  the  light  reaching 
the  eye  directly  from  the  sources  having  a  brightness  greatly 
in  excess  of  that  of  the  objects  viewed,  but  they  may  be  pro- 
duced by  excessive  reflection  from  the  objects  within  view.     In 
factory  lighting  each  lamp  should  be  so  located  that  the  eye 
does  not  see  it  in  the  ordinary  course  of  work,  and  so  shaded 
or  covered  that  brilliant  reflections  are  avoided.     The  desired 
result  can  be  obtained  by  putting  over  the  lamp  an  open  shade 
which  screens  it  and  reflects  downward  much  of  the  light  which 
would  otherwise  be  of  either  no  value  or  actually  detrimental. 
Another  way  of  accomplishing  the  same  result  is  to  surround 
the  lamp  with  a  diffusing  globe  dense  enough  not  to  reveal  the 
form  of  the  actual  light  source  within,  but  to  give  the  effect  of 


GENERAL   LIGHTING   SAFETY   ORDERS.  11 

the  light  pouring  from  the  globe  as  a  whole.     Specific  sugges- 
tions for  various  locations  are  contained  in  this  Appendix. 

5.  In  the  following  descriptive  matter  may  be  found  the 
elements  of  good  illumination  versed  in  such  manner  that  it 
can    be    understood    readily    by    the    nontechnical    mind.     A 
perusal  of  this  subject  will  convince  one  that,  aside  from  the 
humanitarian  standpoint,  the  expense  incurred  in  obtaining 
satisfactory  lighting  will,  in  practically  all  cases,  result  in  good 
financial  returns. 

6.  Minimum    and    desirable    illumination.     The    minimum 
foot-candles  in  Order  1503  specify  the  lowest  illumination  with 
which  the  employee  can  be  properly  safeguarded  against  acci- 
dent.    It  is  to  the  advantage  of  the  employer  to  provide  the  cor- 
responding intensities  of  modern  practice  listed  in  the  follow- 
ing table  of  desirable  illumination,  as  such  provision  results  in 
reduced  eyestrain,  greater  accuracy  of  workmanship,  increased 
production  and  less  spoilage. 

Desirable  Illumination. 

Foot-candles 

at  floor  level  Corresponding 

• — modern  minimum — 

practice  Order  1503 

1.  Roadways    and    yard    thor- 

oughfares    0.05  to  0.25       0.02 

2.  Storage  spaces 0.50  to  1.00       0.25 

3.  Stairs,  stairways,  halls,  hall- 

ways, passageways,  aisles, 
exits,  elevator  entrances 
and  elevator  cars 1.00  to  2.00  0.25-0.50 

4.  Work  not  requiring  discrim- 

ination of  detail 1.00  to  2.00       0.50 

5.  Rough     manufacturing     re- 

quiring  discrimination   of 

detail 2.00  to  4.00       1.00 

6.  Rough     manufacturing     re- 

quiring closer  discrimina- 
tion of  detail 3.00  to  6.00  2.00 

7.  Fine      manufacturing,      ac- 

counting, typewriting 4.00  to  8.00        3.00 

8.  Special  cases  of  fine  work___  7.00  to  15.00       5.00 


12  GENERAL   LIGHTING   SAFETY   ORDERS. 

7.     Table    of    Recommended    Intensities    for    Detailed    Operations    and 
Processes.      (Expressed    in    foot-candles.) 

Classification. 

Assembling. 

Rough  assembling 2-6 

Medium  assembling 3-9 

Fine  assembling 4-12 

Extra  fine  assembling 7-15 

Automobile  manufacturing. 

(See  machine  shops,  paint  shops,  woodworking  shops,  etc.) 

Bakeries. 

Mixing  and  baking 3-9 

Banks. 

Clerical  and  private  offices 4-12 

Desk  and  cage  lighting 4-12 

General  illumination 1-3 

Barber  shops 4-12 

Boiler,  engine  rooms  and  power  houses. 

Boiler  rooms 2-4 

Coal  and  ash  handling 2_4 

Engine  rooms   3-9 

Auxiliary  equipment 2-6 

Oil  switch  and  transformer  rooms 3-9 

Switchboards    3-9 

Storage  battery  rooms 2-6 

Brewing,  distilling  and  bottling. 

Beer  boiling 2-6 

Bottling 3-9 

Clearing  or  resting  and  fermenting 1-3 

Cool  ship  1-3 

Keg  washing 3-9 

Keg  filling 3-9 

Buffing  and  polishing. 

Medium  work 3-9 

Fine  work  4-12 

Button  manufacturing. 

Grading  machines,  wet  and  dry  polishing 1-3 

Grinding  machines,  cutting  blanks  and  shells,  card- 
ing buttons,  hand  turning,  automatic  machines 3-9 

Sorting  of  waste,  sorting  for  thickness 3-9 

Grading  for  color  and  defects 7-15 


GENERAL   LIGHTING   SAFETY   ORDERS.  13 

Classification. 

Candy  making. 

Cooking  over  furnaces 3-9 

Cooling  slabs 3-9 

Cream  beater  machines 3-9 

Dipping  (hand)   3-9 

Dipping   (machine)   3-9 

Moulding  3-9 

Revolving  pan   3-9 

Spinning  bench   3-9 

AWights  and  measures 3-9 

Wrapping  and  packing 3-9 

('•ii'inng  and  preserving. 

Cooking    3-9 

Assorting,  cleaning,  cutting  and  peeling 3-9 

Hand  filling  .__  3-9 

Machine  filling 3-9 

Chemical  works. 

Furnaces    2-6 

Tanks  or  cooking,  extractors,  percolators,  nitrators-  3-9 

Generators  and  stills 2-6 

Drying   2-4 

Evaporators 3-6 

Filtration 3-6 

Grinding    3-9 

Crystallizing    3-6 

Bleaching 3-6 

Electrolytic  cells 3-9 

Clay  products  and  cements. 

Enameling  3_9 

Grinding    2-4 

Filter  press  rooms 2-4 

Moulding  and  pressing 3-6 

Cleaning  and  trimming 3-6 

Coloring  and  glazing 4-12 

Kiln  rooms 2-4 

Kiln  yards -J-2 

Cloth  products.                                                           £fif  £&* 

Cutting 4-12  7-15 

Sewing   (machine) 4-12  7-15 

Si-wing  (hand)   4^-12  7-15 

Pressing   __^ 4-12  7-15 

Inspecting    4-12  7-15 

Cl«>th  treating  (oilcloth,  etc.) 3-9  4-12 


14  GENERAL   LIGHTING   SAFETY   ORDERS. 

Classification. 

Construction — Building,  railway,  tunneling,  etc. 

Indoor    1-3 

Outdoor   £-2 

Dairy  products. 

Separators,  evaporators,  churns,  moulds  and  presses  3-9 

Pasteurizing 3-9 

Bottling,  canning  and  labeling 3-9 

Ice  cream  freezers 3-9 

Depots. 

Baggage  rooms 1-2 

Dining  rooms 3-6 

General  offices 4-8 

Waiting  rooms  2-4 

Loading  platforms 1-2 

Draughting  rooms 7-15 

Electric  manufacturing. 

Coil  and  armature  winding 4-12 

Mica  working  4-12 

Insulation  moulding 4-12 

Other  insulating  processes 4-12 

Storage  battery  moulding  of  grids 3-9 

Lamp  manufacturing  7-15 

Wire  insulating 4-12 

Elevators. 

Freight  and  passenger 1-3 

Fertilizer  manufacturing. 

Cookers,  pressers,  fertilizer  dryers,  fertilizer  mills-  2-6 

Forge  shops  and  welding. 

Rough  forging 2-6 

Fine  forging 3-9 

Drop  forging 3-9 

Foundries. 

Rough  moulding 2-6 

Fine  moulding 3-9 

Core  making 3-9 

Charging  floor 2-4 

Tumbling  and  cleaning 2-6 


GENERAL   LIGHTING   SAFETY   ORDERS.  15 
Classification. 

Glass  works. 

Mix  room 2-6 

Furnace  room 2-6 

Casting  and  lehr 2-6 

Grinding    3-9 

Fine  grinding  and  polishing 4-12 

Glass-blowing  machines 3—9 

Cutting  glass  to  size 3-9 

Glass  cutting  (cut  glass) 7-15 

Beveling 4-12 

Silvering    3-9 

Inspecting  7-15 

Etching  and  decorating 4-12 

Glove  manufacturing.                                                goods.  goods. 

Sorting 1 4-12  7-15 

Cutting    3-9  4-12 

Stitching    4-12  7-15 

Trimming  and  inspecting 4-12  7-15 

Pressing  3-9  4-12 

Knitting 3-9  4-12 

Grinding,  buffing  and  polishing. 

Rough  work 2-6 

Medium  work 3-9 

Fine  work 4^-12 

Halls,  stairways,  passageways  and  aisles 1-2 

Eat  manufacturing.                                                 £•£  ££ 

Forming,  sizing,  pouncing,  flanging,  finish- 
ing and  ironing 3-9  4-12 

Dyeing  and  stiffening 2-6  3-9 

Braiding 2-6  3-9 

Cleaning  and  refining 2-6  3-9 

Sewing   4-12  7-15 

Hospitals. 

Corridors  0.5 

"Wards,  general  (supplemented  by  local) 0.5 

Wards,  with  no  local  lighting 1-3 

Laboratories   , 3-6 

Operating  tables 25-40 

(See  boiler  and  engine  rooms,  laundries,  kitchens, 
dining  rooms,  storage  spaces,  etc.) 


16  GENERAL   LIGHTING  SAFETY   ORDERS. 

Classification. 

Hotels. 

Kitchens 2-6 

Dining  rooms 3-6 

(See  engine  and  boiler  rooms,  offices,  storage  spaces, 
stairways,  passageways,  laundries,  etc.) 

Ice  making 2-6 

Inspecting. 

Rough  inspecting 2-6 

Medium  inspecting 3-9 

Fine  inspecting 4—12 

Extra  fine  inspecting 7-15 

Jewelry  and  watch  manufacturing. 

Bench  work  and  extra  fine  machine  work 7—15 

Machine  work 7—15 

Stamping 7-15 

Engraving 7-15 

Jewel  working 7-15 

Laundries  and  dry  cleaning. 

Sorting  and  marking 3-9 

Washing 2-6 

Mangles  and  machine  ironing 3-9 

Pressing  and  hand  ironing 3—9 

Dry  and  steam  cleaning 3-9 

Leather  manufacturing. 

Cleaning,  tanning,  stretching,  etc 2-6 

Cutting,  fleshing  and  stuffing 3-9 

Finishing  and  scarfing 4-12 

Vats 1-3 

Leather  working.  £*£  *££ 

Grading  and  matching 4—12  7-15 

Cutting  and  scarfing 4r-12  4-8 

Sewing   4-12  7-15 

Pressing  and  winding 3-9  4r-12 

Libraries 3-6 

(See  other  classifications  relating  to  corresponding 
quarters. ) 

Locker,  toilet  and  wash  rooms^^ : - 2-4 


GENERAL  LIGHTING   SAFETY   ORDERS.  It 

Classification. 

Machine  shops. 

Rough  bench  and  machine  work 2-6 

Medium  bench  and  machine  work 3-9 

Fine  bench  and  machine  work 4—12 

Extra  fine  bench  and  machine  work 7—15 

Automatic  machines  (ordinary) 3-9 

Automatic  machines    (fine) 4-12 

Grinding,  buffing  and  polishing,  rough  work 3-9 

Grinding,  buffing  and  polishing,  medium  work 4-12 

Grinding,  buffing  and  polishing,  fine  work 7-15 

Meat  packing. 

Slaughtering   2-6 

Cleaning  and  cutting 3-9 

Cooking 3-9 

Grinding  and  packing ^  3-9 

Canning   3-9 

Milling  and  grain  food  products. 

Cleaning 2-6 

Grinding  or  rolling 2-6 

Baking  or  roasting 3-9 

Mining. 

(See  boiler  and  engine  rooms,  power  houses,  halls, 
stairways  and  passageways,  roadways,  yard  thor- 
oughfares, etc.) 

Offices 4-12 

Oil  refining. 

(See  boiler  and  engine  rooms,  power  houses,  road- 
ways, yard  thoroughfares,  chemical  works,  etc.) 

Packing. 

Rough 2-6 

Medium    3-9 

Fine    4-12 

Paint  manufacturing 2-6 

Paint  shops. 

Dipping  or  spraying 3-9 

Rubbing   3-9 

Firing 2-6 

Hand  painting  and  finishing,  ordinary 3-9 

Hand  painting  and  finishing,  fine 4^12 

Hand  painting  and  finishing,  extra  fine  (automobile 

bodies,  piano  cases,  etc.) 7-15 

3-47806 


18  GENERAL  LIGHTING   SAFETY   ORDERS. 

Classification. 

Paper  'box  manufacturing.  &>oas.  goods. 

Cutting 2-6  3-9 

Machine  folding 2-6  3-9 

Hand  folding 2-6  3-9 

Pasting  and  assembling 2-6  3-9 

Paper  manufacturing. 

Beaters 2-6 

Calendering 3-9 

Machine   3-6 

Grinding 2-6 

Finishing,  cutting  and  trimming 4-12 

Plating. 

Plating 3-9 

Polishing  and  burnishing 3-9 

Printing  industries. 

Linotype  and  monotype 7-15 

Typesetting  7-15 

Composing  stone 7-15 

Matrix  and  casting 3-9 

Miscellaneous  machines 3-9 

Proofreading 4-12 

Presses,  job  and  small  automatic 3-9 

Presses,  rotary,  flat-bed,  etc 3-9 

Lithographing 4-12 

Electrotyping    4-12 

Engraving  7-15 

Receiving  and  shipping 2-6 

Restaurants  (see  hotels). 

Roadways  and  yard  thoroughfares 0.05-0.25 

Rubber  manufacturing  and  products. 

Calendering 3-9 

Grinding 3-6 

Vulcanizing 3-6 

Washing  and  compounding  rolls 3-9 

Schools. 

Auditoriums 2-4 

Blackboards 3-5 

Classrooms,  study  rooms,  libraries,  laboratories 3-9 

Gymnasiums '. 3-6 

Sewing,  drafting 7-15 

Shop  work  (rough) 2-6 

Shop  work  (fine) 4-12 

Stairways,  corridors,  toilets,  hat  and  cloakrooms,  etc.  1-2 

Storage  spaces 0.5-1 


GENERAL   LIGHTING   SAFETY   ORDERS.  19 
Classification. 

Sheet  metal  working. 

Bench  work,  ordinary 3-9 

Bench  work,  fine 4-12 

Punches,  presses,  shears,  stamps  and  welders 4-12 

Spinning 4r-12 

Miscellaneous  machines 3-9 

Shipbuilding. 

( See  machine  shops,  sheet  metal  working,  roadways, 
yard  thoroughares,  woodworking,  assembling,  etc.) 

07                           ,                                                                                   Light  Dark 

Shoe  manuactunng.                                                  goods,  goods. 

Inspecting  and  sorting  raw  material 4-12  7-15 

Cutting 4-12  4-8 

Stitching,  machine 7-15  7-15 

Stitching,  hand 4-12  7-15 

Lasting  and  welding 4-12  4-8 

Hand  turning 3-9  3-9 

Miscellaneous  bench  and  machine  work 3-9  4-12 

Soap  manufacturing. 

Kettle  houses 2-6 

Framing 1-3 

Cutting 2-6 

Stamping,  wrapping  and  packing 3-9 

Soap  chip 2-6 

Soap  powder 2-6 

Filling  and  packing  soap  powder 3-9 

Stairways  (see  halls) . 

Steel  and  iron  mills,  bar,  sheet  and  wire  products. 

Automatic  machines 3-9 

Charging  floor 2-4 

Casting  floor 2-4 

Soaking  pits  and  reheating  furnaces 2-4 

Rolling  mills 3-9 

Shears,  presses,  punches  and  riveters 3-9 

Rod  mill 3-9 

Wire  drawing,  coarse 3-9 

Wire  drawing,  fine 4-12 

Pickling  and  cleaning 2-6 

Stone  cutting. 

Machine  cutting 2-6 

Hand  cutting 2-6 

Carving 3-9 

Polishing 3-9 


20  GENERAL   LIGHTING   SAFETY   ORDERS. 

Classification. 

Store  and  stock  rooms. 

Rough  stock 2-6 

Medium  stock 3-9 

Fine  stock 4r-12 

Stores. 

(Satisfactory  store  lighting  requires  that  considera- 
tion be  given  so  many  different  factors,  such  as 
location,  color  of  finish,  size  and  shape,  location 
and  character  of  displays,  as  to  make  it  impossible 
to  compile  a  complete  list.  The  following  tabu- 
lation is  general,  only,  and  it  is  recommended  that 
expert  advice  be  obtained  where  any  doubt  exists 
as  to  the  proper  allowances  to  be  made.) 

Automobile  showrooms - 3-9 

Art  (light  on  exhibits) 5-10 

Book 3-9 

Baker 2-6 

Butcher 2-6 

China 3-9 

Cigar   4-6 

Clothing 4-12 

Cloak  and  suit 4-12 

Candy 3-6 

Confectionery 3-6 

Decorator 4r-12 

Department  (see  each  department). 

Drug 2-6 

Dry  goods 4-12 

Florist 2-6 

Furniture 3-9 

Furrier 4-12 

Grocery 2—6 

Haberdasher  (men's  furnishings) 4-12 

Hardware 2-6 

Hat   4-12 

Jewelry 4-12 

Millinery 4-12 

Music 2-6 

Notions 3-9 

Piano 3-9 

Rug  racks 10-20 

Shoe 2-6 

Stationery 2-6 

Tailor   4-12 

Tobacco  (see  cigars). 


GENERAL   LIGHTING   SAFETY  ORDERS.  21 
Classification. 

Sugar  refining. 

(See  boiler  and  engine  rooms,  power  houses,  halls, 
passageways,  chemical  works,  etc.) 

Telegraph. 

Operating __  4-12 

Telephone. 

Automatic  exchanges 4-12 

Manual  exchanges 3-9 

Testing. 

Rough 2-6 

Medium 3-9 

Fine 4-12 

Extra  fine 7-15 

Textile  mills. 

n                                                                                                               Light  Dark 

OOttOn —                                                                                             goods.  goods. 

Opening  and  lapping 2-6  2-6 

Carding 2-6  2-6 

Drawing   frame    -     2—6  2—6 

Roving,  spooling,  spinning,  etc 3-9  3-9 

Warping 2-6  2-6 

Slashing  2-6  2-6 

Drawing  in 3-9  3-9 

Weaving 3-9  3-9 

Dyeing 3-9  3-9 

Silk— 

Winding 3-9  3-9 

Throwing   3-9  3-9 

Quilling   and   warping 3-9  4-12 

Weaving 3-9  4-12 

Dyeing   3-9  3-9 

Finishing  3-9  4-12 

Woolen — 

Picking 3-9  3-9 

Washing  and  combing 3-9  3-9 

Carding 2-6  2-6 

Twisting 3-9  3-9 

Dyeing   3-9  3-9 

Drawing  in 3-9  4-12 

Warping 3-9  4-12 

Weaving 4-12  7-15 

Perching 7-15  7-15 

Knitting  machines,  ordinary  and  nappers 3-9  3-9 

Knitting  machines,  flat  and  others 4-12  4-12 

Cordage  mills  __, 3-9  3-9 


22  GENERAL  LIGHTING   SAFETY   ORDERS. 

Classification. 

Tin  can  manufacture. 

(See  sheet  metal  working,  machine  shops,  etc.) 
Tobacco  products — all  operations 3-9 

Warehouses 2-4 

(See  other  classifications.) 
Woodworking. 

Rough  sawing  (sawmills) 2-6 

Sizing,  planing,  rough  sanding,  etc 3-9 

Machine  woodworking,  medium 3-9 

Machine  woodworking,  fine 4-12 

Bench  work,  medium 3-9 

Bench  work,  fine 4-12 

Fine  sanding  and  finishing 4-12 

Gluing  and  veneering 3-9 

Cooperage 3-9 

DAYLIGHT. 

8.  Importance    of    daylight.     Adequate    daylight    facilities 
through   large   window   areas,   together  with  light,   cheerful 
surroundings,  are  highly  desirable  and  necessary  features  in 
every  work  place,  and  they  should  be  supplied  through  the 
necessary  channels  not  only  from  the  humane  standpoint,  but 
also  from  the  point  of  view  of  maximum  plant  efficiency.     The 
unusual  attention  to  gas  and  electric  lighting  in  factories,  mills 
and  other  work  places  during  the  past  few  years ;  the  perfection 
of  various  lamps  and  auxiliaries  by  means  of  which  an  improved 
quality  and  quantity  of  lighting  effects  are  obtained;  and  the 
care  which  has  been  devoted  to  increasing  the  efficiency  in 
various  industrial  operations — all  go  to  emphasize  the  many 
advantages  and  economies  that  result  from  suitable  and  ade- 
quate window  space  as  a  means  for  daylight  in  the  proper 
quantities  and  in  the  right  directions  during  those  portions  of 
the  day  when  it  is  available. 

9.  Three  considerations.     Three  important  considerations  of 
any  lighting  method  are  sufficiency,  continuity  and  diffusion. 
With  respect  to  the  daylight  illumination  of  interiors,  suffi- 
ciency demands  adequate  window  area;   continuity  requires 
(a)  large  enough  window  area  for  use  on  reasonably  dark  days, 
(6)  means  for  reducing  the  illumination  when  excessive,  due  to 
direct  sunshine,  and  (c)  supplementary  lighting  equipment  for 


GENERAL   LIGHTING   SAFETY   ORDERS.  23 

use  on  particularly  dark  days  and  especially  toward  the  close 
of  winter  days;  diffusion  demands  interior  decorations  that  are 
as  light  in  color  as  practicable  for  ceilings  and  upper  portions 
of  walls,  and  of  a  dull  or  mat  finish  in  order  that  the  light 
which  enters  the  windows  or  that  which  is  produced  by  lamps, 
may  not  be  absorbed  and  lost  on  the  first  object  that  it  strikes, 
but  that  it  may  be  returned  by  reflection  and  thus  be  used  over 
and  over  again.  Diffusion  also  requires  that  the  various  sources 
of  light,  whether  windows,  skylights  or  lamps,  be  well  distrib- 
uted about  the  space  to  be  lighted.  Light  colored  surroundings 
as  here  suggested  result  in  marked  economy,  but  their  main 
object  is  perhaps  not  so  much  economy  as  to  obtain  a  result 
that  will  be  satisfactory  to  the  human  eye. 

10.  Requirements.     The  following  requirements  may  now  be 
listed  for  natural  lighting: 

1.  The  light  should  be  adequate  for  each  employee. 

2.  The  windows  should  be  so  spaced  and  located  that  daylight 
conditions  are  fairly  uniform  over  the  working  area. 

3.  The  intensities  of  daylight  should  be  such  that  artificial 
light  will  be  required  only  during  those  portions  of  the  day 
when  it  would  naturally  be  considered  necessary. 

4.  The  windows  should  provide  a  quality  of  daylight  which 
will  avoid  a  glare  due  to  the  sun's  rays  and  light  from  the  sky 
shining  directly  into  the  eye,  or  where  this  does  not  prove  to 
be  the  case  at  all  parts  of  the  day,  window  shades  or  other 
means  should  be  available  to  make  this  end  possible. 

5.  Ceilings  and  upper  portions  of  walls  should  be  maintained 
a  light  color  to  increase  the  effectiveness  of  the  lighting  facil- 
ities from  window  areas.     The  lower  portions  of  walls  should 
be  somewhat  darker  in  tone  to  render  the  lighting  restful  to  the 
eye.     Factory  green  or  other  medium  colors  may  be  used  to 
good  effect. 

11.  Classification.     Means    for    natural    lighting    may    be 
classed  under  three  broad  divisions  as  follows : 

(a)  That  case  in  which  the  windows  are  located  on  the  sides 
of  the  building  or  in  the  framework  of  saw-tooth  construction 
where  diffused  light  from  the  sky  reaches  the  work  during  a 
large  portion  of  the  day. 

(&)  That  case  in  which  windows  are  located  overhead  on  a 
horizontal  or  nearly  horizontal  plane  in  the  form  of  skylights, 


24  GENERAL  LIGHTING   SAFETY   ORDERS. 

thus  furnishing  direct  light  from  the  sky  during  a  large  portion 
of  the  day. 

(c)  That  case  in  which  prismatic  glass  takes  up  the  direct 
light  from  the  sky  and  redirects  it  into  the  working  space. 

Method  (a)  is,  of  course,  the  most  common  of  the  three,  and 
it  may  be  noted  that  the  saw-tooth  or  other  roof -lighting  con- 
structions have  become  very  popular  and  result  in  an  excellent 
quality  and  quantity  of  light  for  given  window  areas,  provided 
the  size  and  location  of  windows  are  in  accord  with  modern 
practice. 

12.  Increasing  the  value  of  floor  space.     Adequate  and  well 
distributed  natural  light  means  that  certain  portions  of  the 
floor  space  which  ordinarily  would  not  be  available  for  work, 
are  converted  into  valuable  manufacturing  space.     In  a  gen- 
eral way,  therefore,  the  average  factory,  mill  or  other  work 
place,  if  properly  designed,  should  possess  natural  lighting 
facilities  which  produce  the  best  practicable  distribution  of 
daylight  illumination. 

13.  Wide  aisles.    With  low  ceilings  and  very  wide  aisles, 
workmen  located  at  the  central  portion  of  the  building  must 
sometimes  depend  for  their  natural  light  on  windows  located 
at  a  considerable  distance  away  from  their  working  position. 
In  these  cases  it  may  be  possible,  in  general,  to  depend  alto- 
gether on  daylight  over  an  entire  floor  space,  even  at  those 
times  of  the  day  when  daylight  conditions  would  be  entirely 
adequate  under  other  circumstances.     This  statement  applies 
to  side  windows  rather  than  to  skylights  or  to  saw-tooth  con- 
struction.    Fig.  1  illustrates  this  feature. 

14.  Varying  conditions.     In  a  case  of  this  kind,  employees 
located  next  to  the  windows  are  furnished  with  suitable  day- 
light in  the  early  morning  and  towards  the  latter  part  of  the 
afternoon,  the  upper  portions  of  the  windows  being  particu- 
larly serviceable  in  lighting  areas  at  some  distance  away  from 
the  windows.     A  southern  exposure,  however,  results  in  such 
excessive  light  from  the  sky  during  the  middle  of  the  day,  that 
heavy  shades  are  nearly  always  pulled  down  so  as  to  cover  the 
entire  window  area.     This  plan  makes  it  necessary  to  use  arti- 
ficial light  throughout  the  larger  part  of  the  office  during  the 
brightest  portion  of  the  day,  and  reduces  the  daylight  at  those 
points  where  it  would  supposedly  be  the  best,  namely,  near  the 


GENERAL   LIGHTING   SAFETY   ORDERS. 


25 


windows.  Here  the  location  of  the  windows  is  a  large  factor 
in  the  excellence  of  the  daylight  conditions,  but  the  manipula- 
tion of  the  shades  is  perhaps  even  more  important.  To  avoid 
such  difficulty,  adjustable  translucent  upper  window  shades 
with  adjustable  opaque  lower  shades  might  be  employed. 


REGION  OFCOM- 
PARITIVE  ABSENCE 
OF  DAYLIGHT.  ARTI- 
FICIAL DAYLIGHT 
REQUIRED  NEARLY 

ALL  DA.Y 


ELEVATION 


0 


/DESKS-, 


000 
0  O  0 


0  O  0 


-50' 


000 


PLAN 

FIG.  1.  Diagram  of  a  large  office 
with  windows  on  one 
side  only. 

15.  Upper  portions  of  windows.     It  should  be  further  noted 
in  this  illustration  that  the  upper  portions  of  the  windows  give 
a  reduced  illumination  in  proportion  to  their  areas,  to  the  floor 
space  near  them.     In  rooms  of  moderate  size,  therefore,  the 
windows  should  be  placed  as  near  the  ceiling  as  practicable. 
When  the  sun  shines*  through  windows  so  located,  the  direct 
light  must  be  reduced  or  diffused.     This  may  be  accomplished 
by  the  use  of  ribbed  glass  in  ordinary  factory  and  mill  build- 
ings, and  in  offices  by  the  use  of  translucent  sunshades  or 
awnings. 

16.  Tempering  the  light.     The  light  due  to  the  sunshine  on 
such  shades  and  awnings  will  be  as  bright  as  ordinary  skylight 
if  the  shade  is  well  chosen,  and  the  ribbed  glass  will  be  still 
brighter.     If  the  windows  are  large,  the  illumination  is  likely 


4— 478C6 


26 


GENERAL.  LIGHTING   SAFETY   ORDERS. 


to  be  too  great  near  the  windows  as  previously  pointed  out  and 
it  should  be  reduced.  This  should  not  be  done,  however,  by 
pulling  down  an  opaque  shade  over  the  top  of  the  windows 
because  the  top  portion  of  the  window  is  the  part  that  is  par- 
ticularly needed  to  give  light  to  the  interior  of  the  room.  The 
better  scheme  is  to  employ  an  opaque  shade  which  should  be 
raised  from  the  bottom  of  the  window.  This  will  reduce  the 
illumination  near  the  window  without  affecting  it  over  the 
interior  of  the  room  to  any  marked  degree. 

17.  Bench  locations.  Fig.  2  shows  how  benches  are  com- 
monly located  with  respect  to  windows,  so  that  the  light  received 
on  the  work  may  be  most  satisfactory.  This  sets  a  certain 


<    CEILING-*               |                 7Q. 

BENCH  SURFACE-      ]  ASSEMBLY    WORK; 

^^~"        \ 

"1                                      / 

}„„,„>;;,„,     '< 

ELEVATION 

'! 

1 

"VBENCH-I      -i  -u 

li 

I  

•+  J 

(  
! 

• 

1] 

1 

*•                     - 

V-BENCH-,         1    - 
*        l 

1 

///S//SS/S/////J//) 

PLAN 

FIG.  2.  Diagram  showing  benches  located 
with  respect  to  the  windows  so 
as  to  receive  the  natural  light 
advantageously. 

limitation  upon  the  possible  arrangement  of  the  work  over 
the  floor  space,  depending  on  the  way  daylight  is  furnished  to 
the  floor  area.  This  limitation  can  be  eliminated  almost  com- 
pletely in  the  case  of  artificial  light  through  a  uniform  dis- 
tribution of  lamps  overhead.  This  statement  applies  to  those 
cases  where  natural  light  is  transmitted  through  side  windows, 
and  includes  a  feature  specially  noticeable  in  buildings  of  more 
than  one  story.  In  contrast,  the  work  may  be  arranged  almost 
independently  of  the  natural  light  in  buildings  where  the 
natural  light  is  furnished  by  overhead  windows  or  through 
the  means  of  saw-tooth  construction. 

18.  Window  glasses.  Both  translucent  and  clear  glass  are 
employed  for  factory  and  mill  windows.  There  is  a  slight 
reduction  in  the  transmitted  light  through  ordinary  translucent 


GENERAL  LIGHTING   SAFETY   ORDERS.  27 

vvire  glass,  but  it  is  often  required  by  insurance  regulations 
for  a  deduction  in  the  fire  risk  where  a  given  building  is  located 
in  close  proximity  to  other  buildings.  Wire  glass  is  also  used 
quite  generally  with  steel  window  frames,  here  being  an  added 
protection  from  the  standpoint  of  fire  risk.  Wire  glass  may 
be  obtained  in  clear  form,  but  its  expense  in  contrast  to  the 
translucent  form  is  such  as  ordinarily  to  prohibit  its  use  for 
industrial  purposes. 

19.  Wire  glass.     Wire   glass,   also  known  as  ribbed  glass, 
should  be  used  and  is  advocated  for  practically  all  factory  and 
mill  windows  where  prisms  are  not  required.     Wires  of  rather 
open  mesh  cause  so  little  reduction  in  light  as  to  warrant  no 
mention  of  this  .feature.     Special  care  should  be  taken  to  get 
such  glass  as  is  smooth  both  on  the  flat  side  and  on  the  ribbed 
side  to  facilitate  cleaning.     Wire  or  ribbed  glass  gives  better 
diffusion  than  plain  glass. 

20.  Prism  glass.     Where  the  sky  outside  of  the  windows  is 
obstructed  by  buildings,  prism  glass  is  recommended  if  the  room 
is  deep.     Different  kinds  of  prisms  can  not  be  used  to  advan- 
tage interchangeably.     The  amount  of  prism  glass  required 
in  any  case  depends  much  upon  the  surroundings  and  to  obtain 
excellent  results,  of  which  such  glass  is  capable,  it  must  be 
used  intelligently. 

21.  Skylights.     Skylights  are  sometimes  installed  in  long 
narrow  continuous  strips  in  a  sloping  roof.     The  ribs  of  the 
ribbed  glass  are  generally  so  arranged  that  it  is  convenient 
to  make  them  at  right  angles  to  the  length  of  the  strips.     The 
result  is  that  the  sunshine  is  diffused  by  the  ribs  over  a  narrow 
area  parallel  to  the  strip  of  skylight,  thus  lighting  one  part 
of  the  room  much  more  brilliantly  than  the  remainder.     If  the 
ribs  are  installed  to  run  parallel  to  the  strips,  they  will  give 
a  much  more  general  distribution  of  the  sunlight.     In  the 
foregoing,  the  word  strip  refers  to  the  long  belt  of  skylight  and 
not  to  the  individual  sheet  of  glass.     Ribbed  glass  in  vertical 
windows  should  generally  be  placed  with  the  ribs  horizontal. 
They  thus  roughly  fulfill  some  of  the  functions  of  prisms. 

22.  Dirt  accumulations.     While  translucent  wire  or  ribbed 
glass  reduces  the  amount  of  light  transmitted  through  the 
windows,  the  roughness  of  the  outside  surface  of  such  glass 
often  causes  accumulations  of  dust  and  dirt,  which  are  more 


28  GENERAL  LIGHTING   SAFETY   ORDERS. 

to  blame  for  the  reduction  of  transmitted  light  in  some  cases 
than  the  translucent  nature  of  the  glass  itself.  Remedies  of 
this  difficulty  are  to  secure  smooth  glass  and  to  resort  to 
frequent  cleaning. 

23.  Wire  glass  as  a  safeguard.     Wire  glass  for  skylights  is, 
of  course,  a  practical  necessity  as  a  safeguard  against  accidents 
due  to  accidental  breakage  of  the  glass  or  due  to  objects  falling 
on  top  of  the  glass. 

24.  Sunshine  not  desirable.     In  all  the  work  of  providing 
natural  light,  it  should  be  kept  in  mind  that  direct  sunshine 
in  itself,  from  the  illumination  standpoint,  but  irrespective  of 
sanitary  conditions,  is  not  wanted.     The  idea  that  sunshine  is 
the  important  item  is  a  common  but  an  erroneous  impression. 
For  example,  in  saw-tooth  construction,  the  windows  do  not 
face  the  south  to  get  all  the  sunshine  possible,  but  they  face 
the  north  to  exclude  the  sunshine.     Ordinarily  windows,  on 
the  other  hand,  face  all  directions  because  not  enough  light 
can   be   distributed   to   interiors  from   north   windows   alone. 
Windows  on  the  other  than  north  fronts  admit  sunshine  to  be 
sure,  and  this  makes  sun  shades  and  awnings  necessary  to 
exclude  the  excessive  brightness. 

VALUE  OF  ADEQUATE  ILLUMINATION. 

25.  Factory  and  mill  owners  are  concerned  in  the  matter 
of  securing  the  largest   output  for   a   given   manufacturing 
expense.     An   improved   machine  tool  capable  of  increasing 
the  product  for  given  labor  costs  is  most  attractive,  provided 
its  first  cost  is  within  returnable  limits  out  of  the  larger  profits. 
Improved  small  tools,  better  methods  of  handling  material, 
adequate    crane    service,    fire    protection,    good    shop    floors, 
accurate  and  efficient  timekeeping  methods,  and  similar  items, 
vitally  concern  the  shop  manager ;  money  is  expended  to  realize 
excellence    in   these   features   because   they    afford   increased 
economies  and  protection,  thus  resulting  in  a  higher  efficiency 
of  the  plant. 

26.  Energy  consumption  a  minor  item.     Many  arguments 
leading  to  the  sale  of  gas  and  electric  lamps  for  use  in  factory 
and  mill  buildings  are  based  on  reducing  the  lamp  operation 
cost  of  substituting  a  new  for  an  older  system.     Arguments 
of  this  kind  are  of  value,  however,  only  when  such  a  reduction 


GENERAL  LIGHTING   SAFETY   ORDERS.  29 

in  operation  cost  can  be  effected  without  sacrifice  in  the  ade- 
quacy of  the  illumination.  It  would  be  a  poor  policy,  in  the 
extreme,  to  argue  a  saving  in  energy  consumption  by  the  sub- 
stitution of  one  type  of  lamp  for  another  on  a  basis  of  equal 
candlepower  in  both  old  and  new  systems. 

27.  Effect  of  good  light  on  production.    Arguments  of  a 
convincing  nature,  which  insure  to  the  factory  or  mill  man- 
ager   an    increased    output    through    improved    illumination 
service,   are  of  importance  and  even  greater  at  times  than 
reductions  in  the  cost  of  illumination  for  the  same  quantities 
of  light.     In  view  of  the  fact  that  resulting  advantages  of 
superior  illumination  on  increased  output  are  apt  greatly  to 
exceed  economies  in  operation  cost  as  regards  the  lighting 
system,  it  is  a  distinct  advantage  to  direct  and  hold  the  atten- 
tion on  the  former  rather  than  on  the  latter.     This  statement 
will  be  more  apparent  when  interpreted  into  definite  items 
as  follows: 

28.  Advantages  of  good  light.    While  the  necessity  of  good 
natural  and  artificial  light  is  so  evident  that  a  list  of  its  effects 
may  seem  commonplace,  these  same  effects  are  of  such  great 
importance  in  their  relation  to  factory  and  mill  management, 
that  they  are  well  worth  careful  attention.     The  effects  of  good 
light,  both  natural  and  artificial,  and  of  bright  and  cheerful 
interior  surroundings,  include  the  following  items: 

1.  Reduction  of  accidents. 

2.  Greater  accuracy  in  workmanship. 

3.  Increased  production  for  the  same  labor  cost. 

4.  Less  eyestrain. 

5.  Promote  better  working  and  living  conditions. 

6.  Greater  contentment  of  the  workmen. 

7.  More  order  and  neatness  in  the  plant. 

8.  Supervision  of  the  men  made  easier. 

In  this  list  it  will  be  noted  that  items  4,  5,  6,  7  and  8  all  have 
a  bearing  on  accident  prevention. 

29.  Interpreting  the  advantages  of  good  light.    While  the 
major  consideration  in  the  eyes  of  the  factory  or  mill  owner 
is  undoubtedly  and  quite  naturally  the  money  value  of  good 
light  in  the  larger  return  of  both  quantity  and  quality  of  work 
which  may  result  from  the  installation  of  a  superior  as  com- 
pared with  an  inferior  lighting  system,  it  should  be  noted  that 
it  is  very  difficult  to  interpret  into  dollars  and  cents  the  value 


30  GENERAL  LIGHTING   SAFETY   ORDERS. 

of  good  light  made  possible  by  such  returns.  This  difficulty 
is  due  to  the  necessity  of  keeping  all  conditions  in  a  factory  or 
mill  section  absolutely  constant  while  varying  the  amount  of 
illumination  from  poor  to  good  conditions,  in  an  effort  to 
determine  the  output  and  its  dependency  on  the  light  facilities. 
As  accurate  data  becomes  available,  giving  the  increases  in 
production  for  certain  specific  improvements  in  artificial  light- 
ing, it  will  doubtless  prove  helpful  to  a  proper  interpretation 
of  adequate  light  and  its  worth  to  any  plant. 

The  eight  foregoing  points  are  emphasized  as  forming  the 
most  important  features  in  the  problem  of  good  lighting. 
Although  difficult  to  interpret  into  money  values,  and  some- 
what intangible,  they  are  indisputable  arguments  in  favor  of 
the  best  available  illumination  from  the  standpoint  of  the 
factory  or  mill  owner. 

30.  Practical  example.     Continuing  from  the  manufacturer 's 
point  of  view,  it  may  be  said  that  certain  assumptions  as  to 
energy  cost,  cleaning,  interest  and  depreciation,  show  that  the 
annual  operation  and  maintenance  cost  for  the  illumination 
of  a  typical  shop  bay  of  640  square  feet  area,  may  be  taken 
at  $50.00.     If  five  workmen  are  employed  in  such  a  bay  at  an 
average  wage  of  say  25  cents  per  hour,  the  gross  wages  of  the 
men  in  such  a  bay,  plus  the  cost  of  superintendence  and  indi- 
rect shop  expense,  may  equal  from  $5,000  to  $7,000  per  annum. 
In  a  case  of  this  kind,  therefore,  the  lighting  will  cost  from 
•fa  to  1  per  cent  of  the  wages,  or  the  equivalent  of  less  than 
4  to  6  minutes  per  day.     We  may  roughly  say  that  a  poor 
lighting  system  will  cost  at  least  one-half  this  amount  (some- 
times even  more  through  the  use  of  inefficient  lamps  and  a  poor 
arrangement  of  lamps),  or  the  equivalent  of  say  2  to  3  minutes 
per  day.     Nearly  all  factories  and  mills  have  at  least  some 
artificial  light,  hence,  in  general,  if  good  light  enables  a  man 
to  do  better  or  more  work  to  the  extent  of  from  2  to  3  minutes 
per  day,  the  installation  of  good  lighting  will  easily  pay  for 
the  difference  between  good  and  bad  light,  through  the  time 
saved  for  the  workmen. 

31.  Actual  losses.     Superintendents  have  stated  in  actual 
instances,  that  due  to  poor  light  their  workmen  have  lost  much 
time,  sometimes  as  much  as  from  one  to  two  hours  per  day  on 
certain  days.     If  good  light  will  add  an  average  of  say  one- 
half  an  hour  per  day  to  the  output,  these  30  additional  effective 


GENERAL  LIGHTING  SAFETY   ORDERS.  31 

minutes  represent  an  increase  in  output  of  5  per  cent,  brought 
about  through  an  expenditure  equal  to  \  of  1  per  cent  of  the 
wages  for  improved  lighting,  or  a  saving  equal  to  ten  times  the 
expense. 

OLD  AND  NEW  LAMPS. 

32.  The   inadequate   means   available   for  illumination   by 
artificial  methods  in  the  past  have  contributed  to  the  slowness 
of  an  appreciation  of  the  features  of  artificial  light  which 
influence  the  working  efficiency  of  the  eye.     Open  flame  gas 
burners,  carbon  incandescent  and  arc  lamps,  practically  the 
only  illuminants  available  ten  years  or  so  ago,  play  but  a 
small  part  in  the  present  approved  methods  of  factory  and 
mill  lighting. 

33.  New  lamps.     The  large  variety  of  comparatively  new 
lamps  available  for  factory  and  mill  lighting  includes  the 
mercury  vapor,  tungsten,   gas-filled  tungsten,  metallic  flame 
or  magnetic  arc,  the  flame  carbon  arc,  the  quartz  mercury 
vapor,    and    various   types   of   gas    arc    lamps.     Remarkable 
improvements  have  thus  been  made  in  both  the  electric  and 
gas  lighting  fields,  the  same  general  rules  of  applying  the 
lamps  covering  both  of  these  fields.     Possibilities  in  factory 
and  mill  lighting  are  now  attainable  which,  before  the  intro- 
duction of  these  new  lamps,   were   either  unthought  of  or 
impossible.     Consideration   of  the   eye   as   a  delicate   organ, 
together  with  the  new  ideas  of  the  items  which  affect  its  comfort 
and  efficiency,  have  resulted  in  establishing  certain  principles 
in  illumination  work,  and  have  directed  attention  naturally 
and  in  a  growing  manner  to  the  proper  use  and  application  of 
these  new  lamps. 

EFFECTS  ON   FACTORY  AND  MILL   LIGHTING   PRODUCED 
BY  MODERN   LAMPS. 

34.  With  the  introduction  of  these  new  gas  and  electric 
lamps,  broader  possibilities  have  been  presented  in  factory 
and  mill  lighting.  The  use  of  units  of  sizes  adapted  to  the 
purposes,  allows  results  which  it  has  been  hitherto  impossible 
to  obtain  satisfactorily,  either  by  the  arc  lamp,  carbon  filament 
or  open  flame  gas  burner,  formerly  available. 


32  GENERAL   LIGHTING   SAFETY   ORDERS. 

35.  New  possibilities.     It  is  evident  that  the  introduction  of 
the  many  new  lamps  has  made  possible  what  may  be  termed 
a  new  era  in  industrial  illumination,  a  distinctive  feature  of 
which  is  the  scientific  installation  of  the  lighting  units,  suiting 
each  to  the  location  and  class  of  work  for  which  it  is  best 
adapted.     Before  the  availability  in  recent  years  of  medium 
sized  gas  and  electric  units  the  choice  of  the  size  of  unit  for 
a  given  location  was  often  no  choice  at  all.     In  many  cases,  due 
to  small  clearance  between  cranes  and  ceilings,  or  other  con- 
ditions making  it  necessary  to  mount  the  lamps  very  high  above 
the  floor,  but  one  size  or  type  of  unit  was  available,  the  carbon 
filament  or  open  flame  gas  burner  in  the  former,  and  the  arc 
lamp  in  the  latter  case. 

36.  Low  ceilings.    For  low  ceilings,  up  to  18  feet,  the  use 
either  of  carbon  filament,  open  flame  gas  burner,  or  arc  lamps 
resulted  usually  in  anything  but  uniform  light  over  the  work- 
ing plane,  and  often  produced  merely  a  low  general  light 
which  was  practically  useless  for  the  individual  machine.     In 
such  instances,  individual  lamps  had  to  be  placed  over  and  close 
to  the  machines.     With  this  arrangement,  a  relatively  small 
area  is  lighted  by  each  lamp  and  the  metal  shades  usually 
employed  serve  only  to  accentuate  the  "spot  lighting"  effect. 
Such  a  form  of  illumination  for  factory  and  mill  work  is 
unsatisfactory  and  inefficient,  but,  as  stated,  was  in  the  past 
in  many  cases  the  only  available  scheme.     The  absence  of 
lamps  of  the  proper  size  is  no  longer  an  excuse  for  the  exist- 
ence of  such  conditions  in  industrial  plants. 

GENERAL   REQUIREMENTS  OF  ARTIFICIAL  LIGHTING. 

37.  The  following  requirements  for  factory  and  mill  lighting 
are  made  all  the  more  important  by  the  peculiar  limitations  and 
the  wide  variety  of  conditions  to  be  found  in  factory  and  mill 
buildings  and  in  factory  and  mill  work : 

1.  Sufficient  illumination  should  usually  be  provided  for 
each  workman  irrespective  of  his  position  on  the  floor 
space. 

2.  The  lamps  should  be  installed  and  selected  so  as  to 
avoid  eyestrain  to  the  workmen. 

3.  The  lamps  should  be  operated  from  sources  of  supply 
which  will  insure  reliable  illumination  results,  particularly 
on  account   of   the   demoralizing   effect  by   intermittent 
service,  just  when  the  light  may  be  most  needed. 


GENERAL   LIGHTING  SAFETY   ORDERS.  33 

4.  Adequate  illumination  should  be  provided  from  over- 
head lamps  so  that  sharp  shadows  may  be  prevented  as 
much  as  possible,  and  in  such  measure  that  individual 
lamps  close  to  the  work  may  be  unnecessary  except  in 
special  cases. 

5.  The  type  and  size  of  lamp  should  be  adapted  to  the 
particular  ceiling  height  and  class  of  work  in  question. 

6.  In  addition  to  the  illumination  provided  by  overhead 
lamps,  individual  lamps  should  be  placed  close  to  the  work 
if  they  are  absolutely  necessary  in  the  eyes  of  a  lighting 
expert,  and  in  such  cases  the  lamps  should  be  provided 
with  suitable  opaque  reflectors. 

These  requirements  may  now  be  met  by  means  of  the  new 
types  of  gas  and  electric  lamps,  one  type  of  which  can  usually 
be  found  for  practically  each  factory  and  mill  location,  espe- 
cially adapted  to  the  general  physical  conditions  of  the  location 
as  typified  by  the  clearance  between  cranes  and  ceiling  and 
other  similar  items. 

OVERHEAD   AND   SPECIFIC   METHODS  OF  ARTIFICIAL 
LIGHTING. 

38.  Factory  and  mill  lighting  may  be  classified  under  two 
general   divisions:  First,    distributed   illumination    furnished 
from  lamps  mounted  overhead ;  and  second,  distributed  illumi- 
nation furnished  by  individual  lamps  located  close  to  the  work. 
For   practical    purposes   this    classification   is   sufficient.     In 
numerous  cases  a  combination  of  these  two  methods  becomes 
necessary. 

39.  Mounting  the  lamps  high.    Where  the  lamps  are  high 
enough  to  be  out  of  the  line  of  ordinary  vision,  and  are  of  a 
size  and  so  spaced  as  to  furnish  illumination  at  any  position 
on  the  floor  where  work  may  be  carried  on,  the  system  is 
referred  to  as  the  overhead  method  of  lighting.     This  method 
has  many  advantages.     Its  general  adoption,  which  has  been 
somewhat  slow,  has  increased  with  the  appearance  of  the  many 
new  types  of  lamps  and  with  the  growing  appreciation  of  the 
value  of  good  lighting. 

40.  Where  a  small  amount  of  general  or  overhead  lighting 
is  coupled  with  specific  lighting  from. individual  lamps,  a  large 
part  of  the  floor  space  in  many  shops  is  in  relative  darkness, 
and  much  dependence  must  be  placed  on  the  hand  lamps  close 
to  the  work.     The  small  number  of  overhead  lamps  generally 


34  GENERAL  LIGHTING   SAFETY   ORDERS. 

used  in  such  cases  furnishes  merely  a  small  amount  of  addi- 
tional illumination  over  the  floor  space  which  is  not  sufficient 
to  be  of  much  value.  However,  where  sufficient  intensity  is 
provided  by  general  illumination,  this  is  often  a  very  effective 
means  of  lighting  a  large  workroom. 

41.  Low  ceiling.     Locations  with  low  ceilings,  until  recently, 
have  been  lighted  by  the  individual  hand  lamp  method,  because 
the  old  carbon  filament  lamps,  being  of  low  candlepower,  could 
not  well  be  used  close  to  the  ceiling,  while  the  old  type  of  arc 
lamp  was  often  impracticable,  due  to  its  large  physical  size, 
as  well  as  its  relatively  high  candlepower.     This  statement  is 
subject  to  some  modification,  because  low  candlepower  units 
have  sometimes  been  used  in  clusters  for  low  ceilings  as  a  com- 
promise between  a  single  small  or  a  single  large  unit,  this 
scheme  being,  however,  usually  insufficient  and  unsatisfactory 
in  comparison  with  modern  methods  of  lighting.     In  a  partic- 
ular manner,  therefore,  suitable  illumination  has  been  difficult 
with  low  ceilings. 

42.  New  types  of  gas  and  electric  lamps  have  a  range  of 
candlepower  from  very  low  to  very  high  values,  and  the  over- 
head system  with  the  elimination  of  individual  lamps  is  thus 
possible ;  in  other  words,  a  size  of  gas  or  electric  lamp  may  now 
be  selected  from  a  large  available  list  of  sizes  for  nearly  every 
factory  or  mill  condition. 

VARIOUS  LOCATIONS   ILLUSTRATED.* 

43.  Figs.  3  to  12  inclusive  are  given  to  indicate  how  the 
problem  of  adequate  illumination  has  been  solved  in  a  number 
of  actual  instances,  and  the  following  notes  apply  to  some  of 
the  considerations  involved. 

There  are  two  main  items  to  consider  in  deciding  for  or 
against  high  candlepower  lamps  for  the  factory  or  mill.  First, 
how  high  are  the  lamps  to  be  mounted;  and  second,  will  the 
light  at  any  given  point  on  the  machines  or  other  operations 
be  satisfactory  if  it  comes  from  a  few  lamps  or  should  it  come 
from  many  sources?  If  the  ceiling  or  overhead  construction 
is  under  16  feet,  lamps  of  high  candlepower  can  hardly  be 
used  in  sufficient  numbers  to  produce  uniform  illumination 
over  the  floor  space.  If  they  are  to  be  mounted  at  a  height 

*Figs.  8  to  12  inclusive  are,  in  general,  arranged  in  the  order  of  their 
mounting  heights.  The  low  mounting  heights  are  shown  in  the  earlier 
illustrations  and  the  higher  mountings  in  the  later  views. 


GENERAL   LIGHTING   SAFETY   ORDERS.  35 

between  16  and  25  feet,  it  is  largely  a  question  of  whether 
light  from  a  relatively  few  lamps  will  produce  satisfactory 
results.  For  mounting  heights  over  25  feet,  lamps  of  high 
candlepower  possess  some  advantages,  chief  of  which  is  their 
large  volume  of  light  for  given  energy  consumed,  always  pro- 
vided the  light  is  effectively  directed  towards  the  floor. 

44.  Three  groupings.     These  three  groupings  by  mounting 
heights  are  conveniently  shown  in  Figs.  15,  16,  17  and  18.     In 
Fig.  15,  a  single  shop  bay  with  a  ceiling  height  of  12  feet  is 
shown  as  typical  of  the  first  grouping.     The  single  high  candle- 
power  lamp  furnishes  approximately  the  same  amount  of  light 
to  the  machines  as  do  the  eight  small  lamps.     Note,  however, 
that  the  illumination  from  the  large  lamp  is  not  nearly  as 
uniform  as  that  from  the  small  lamps,  although  the  spacing 
of  both  the  small  and  the  large  lamps  as  represented  in  this 
illustration  is  typical  of  many  actual  installations.    Note  also 
that  the  shadows  cast  by  the  large  lamp  at  certain  portions  of 
the  floor  space  must  be  so  marked  as  to  make  the  illumination 
it  furnishes  very  inferior  in  this  respect  to  the  illumination 
from  the  smaller  lamps,  because  of  their  larger  number. 

Here,  if  the  number  of  large  lamps  for  the  given  floor  area 
be  increased  in  an  endeavor  to  make  the  illumination  more  uni- 
form and  to  reduce  the  shadows,  the  expense  as  compared  with 
that  for  smaller  lamps,  makes  the  large  lamps  a  very  unfavor- 
able proposition.  These  two  features  are  the  basis  for  stating 
that  in  general  large  lamps  are  not  desirable  for  mounting 
under  16  feet,  and  an  analysis  of  conditions,  together  with 
a.  careful  and  unbiased  comparison  with  the  illumination 
produced  by  smaller  lamps,  will  nearly  always  bear  out  this 
conclusion. 

45.  Second  grouping.     In  Fig.  17,  a  20-foot  ceiling  has  been 
selected  as  typical  of  the  second  grouping,  a  single  shop  bay 
being  shown.     Here  the  work  is  assumed  to  be  rough  assembly, 
mostly  on  horizontal  surfaces,  and  the  single  high  candlepower 
lamp,  besides  giving  more  nearly  uniform  illumination,  because 
the  light  is  distributed  more  broadly  due  to  the  increased 
height,   is   correspondingly   more  satisfactory   as  to  shadows 
produced   by   the  large   lamp   in   the   preceding   illustration 
(Fig.  15),  on  account  of  the  improved  direction  in  which  much 
of  the  light  reaches  the  work.     In  this  case,  the  arrangement 


36  GENERAL  LIGHTING   SAFETY   ORDERS. 

of  both  large  and  small  lamps  is  typical  of  many  existing 
installations. 

46.  In  Fig.  16,  however,  although  the  height  is  the  same  as 
in  Fig.  17,  the  work  is  quite  different,  being  conducted  on  the 
inside  of  large  vertical  tanks.     It  would  obviously  be  impos- 
sible to  perform  this  work  by  the  light  from  the  single  large 
lamp  as  Well  as  with  that  from  the  larger  number  of  medium 
sized  lamps,  even  if  the  actual  amount  of  light  from  each  was 
the  same,  on  account  of  the  poor  direction  of  the  light  at  cer- 
tain positions  of  the  work  from  a  single  unit  in  such  a  case. 
The   medium   sized   lamps   furnish   approximately   the   same 
quantity  of  light  and  yet  no  matter  where  the  tanks  may  be 
placed,  they  will  receive  considerable  light  from  the  medium 
sized  lamps  directly  over  or  nearly  over  them,  at  least  far  more 
than  is  apt  to  reach  them  from  a  single  unit  in  every  other 
bay  (the  assumed  arrangement  of  the  large  lamps). 

47.  For  this  second  grouping  of  mounting  heights,  then,  the 
large  lamps  may  or  may  not  be  adapted,  depending  on  whether 
the  reduction  of  shadows  is  of  much  importance,  as  is  the  case 
in  Fig.  16.     The  large  lamp  is,  however,  more  likely  to  be 
satisfactory  here  than  in  the  first  case  (Fig.  15),  because  of 
the  better  distribution  of  the  light  due  to  the  higher  mounting, 
a  fact  made  evident  in  Figs.  15  and  17  on  account  of  the 
decreased  number  of  small  lamps  and  the  increase  in  their 
size  made  possible  in  Fig.  17  as  compared  with  Fig.  15,  where 
the  mounting  is  lower.     By  the  same  line  of  argument,  it  can 
be  shown  that  for  higher  mountings,  large  lamps  are  still  more 
likely  to  prove  satisfactory. 

48.  In  Fig.  16,  the  number  of  large  lamps  might  have  been 
increased  for  the  given  floor  area,  but  to  have  done  so  would 
mean  that  the  cost  for  the  energy  and  upkeep  to  maintain 
them  would  be  excessive  in  comparison  with  the  smaller  types 
of  lamps. 


GENERAL  LIGHTING   SAFETY   ORDERS. 


37 


FIG  3  Night  view  of  a  rather  low  factory  section  showing  tungsten  lamps 
of  the  100-watt  size  in  bowl  reflectors  mounted  13  feet  above  the 
iloor. 


FiG.  4.  Night  view  showing  lighting  in  low  store  section,  400-watt  tungsten 
lamp  in  18-Inch  dense  semi-indirect  bowls.  Ceiling  height  13  feet. 
Note  the  comparative  absence  ef  shadows. 


38 


GENERAL  LIGHTING   SAFETY   ORDERS. 


FIG.  5.  An  example  of  yard  or  alleyway  lighting,  200-watt  tungsten  lamps  in 
reflectors  with  a  mounting  height  of  20  feet.  Note  the  evenness  of 
illumination  and  the  absence  of  shadows.  Twenty-five  per  cent  of 
the  accidents  in  manufacturing  plants  are  due  to  poor  illumination. 


6.  Night  view  of  a  planing  mill  showing  an  installation  of  250-watt 
tungsten  lamps  with  a  16 -foot  mounting.  Note  the  excellent  dis- 
tribution of  the  light  and  the  comparative  absence  of  shadows.  This 
is  an  example  of  the  overhead  method  of  lighting. 


GENERAL   LIGHTING   SAFETY   ORDERS. 


39 


FIG.  7. 


Night   view   of  factory  section,    400-watt   bowl   type  reflectors  with 
29-foot  mounting  height. 


FIG.   8. 


Night   view  of  open  hearth   pouring  floor  with   750-watt   reflectors, 
35-foot  mounting  height  and  40-foot  spacing. 


40 


GENERAL  LIGHTING   SAFETY   ORDERS. 


FIG.  9.  Night  view  of  factory  section  with  relatively  high  mounting  of 
250-watt  tungsten  lamps.  The  lamps  are  20  feet  above  the  floor. 
Note  the  excellent  distribution  of  the  light  and  the  shielding  effect 
of  the  girders  which  serve  to  reduce  the  glare  as  one  looks  down 
the  aisle. 


FIG.   10. 


Night  view  of  arc  lamp  installation  with  40-foot  mounting  at  center 
of  picture  and  20-foot  at  sides.     Excellent  distribution. 


GENERAL   LIGHTING    SAFETY    ORDERS. 


41 


FIG.   11.     Day  view  of  relatively  high  s««ti»n,  showing  a  system  of  gas  lighting. 


FIG.  12. 


High  section  showing  a  system  of  mercury-vapor  lamps.     Note  the 
excellent  distribution  of.  light  over  the  floor  area. 


42 


GENERAL  LIGHTING   SAFETY   ORDERS. 


FIG.  13. 


Bad  lighting.     Bare  lamps  produce  a  glare  which  Is  harmful  and 
renders  the  Illumination  very  ineffective.     Compare  with  Fig.  14. 


Fio.  14.     Example  of  good  tungsten  lighting. 


GENERAL   LIGHTING   SAFETY   ORDERS. 


43 


)W  POWER 
UNITS 


HIGH  POWER  UNIT 


ELEVATION 


PLAN 

FIG.  15.  Diagram  showing  alternate 
schemes  for  lighting  a 
low  factory  section. 
This  contrasts  the  use 
of  large  and  small 
lamps  for  a  mounting 
height  of  12  feet. 


ELEVATION 


'.LOW 

POWER  UNlTi 

^   4* 

«JHIGH  POWER  UNIT  £ 

i    >BENCHES 

*--4-            4         j   4 

PLAN 


FIG.  16.  Diagram  contrasting  the 
use  of  large  and  medium 
sized  lamps  for  mount- 
ing height  of  20  feet. 


PLAN 

FIG.  17.  Diagram  of  same  factory 
space  shown  in  Fig.  16, 
but  with  a  different  class 
of  work.  This  view  con- 
trasts the  use  of  large 
and  medium  sized  lamps 
for  a  20-foot  mounting. 


44 


GENERAL   LIGHTING  SAFETY   ORDERS. 


49.  Third  grouping.  In  Fig.  18,  the  third  grouping  of 
mounting  heights  is  shown  with  the  lamps  about  50  feet  above 
the  floor.  In  this  illustration  the  distribution  of  the  light 
from  the  large  lamps  will  be  far  more  satisfactory,  both  for 
flat  and  tall  work  than  in  the  two  preceding  cases.  It  will  be 
noted  further  that  the  increased  height  of  the  lamp  causes  the 
light  to  fall  in  such  directions  as  to  distribute  it  evenly  over 


CRANE  RUN-WAY- 


MACHINE  TOOLS  AND  HEAVY  ASSEMBLY 
WORK  LOCATED  ON  THIS  FLOOR  AREA'^ 


ELEVATION 


[HIGH  POWER  UNIT 


_BAYJNTER5EC1IPN: 
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_   ; BAY  INTERSECTION-... _J. 


BAY   INTERSECTION— « _i 


'HIGH  POWER  UNIT 
*-$  PLAN 

FIG.   18.     Diagram  showing  the  use  of  large  lamps 
for  a  mounting  height  of  50  feet. 

the  entire  floor  space  taken  care  of  by  this  one  lamp  in  much 
better  shape  than  for  the  lower  mounting  heights.  (See  also 
Pigs.  19  to  23,  inclusive.) 

LIGHTING  CIRCUITS   FOR   ELECTRIC  LAMPS  AND  SUPPLY 
MAINS  FOR  GAS  LAMPS. 

50.  The  question  of  lighting  circuits  is  mentioned  here  with 
particular  reference  to  factory  and  mill  conditions,  where 
motor  loads  are  apt  to  be  large  in  comparison  to  the  energy 


GENERAL   LIGHTING   SAFETY   ORDERS. 


45 


consumption  of  electric  lamps  which  are  in  service.  In  some 
cases;  the  proportion  of  motor  load  to  lighting  .load  is  in  the 
ratio  of  10  to  1,  in  others  7  to  1,  and  so  on,  and  the  varying 
demands  on  the  circuits  by  motors  may  greatly  affect  the  lamps. 
Hence  it  is  important  to  maintain  strictly  separate  supply 
circuits  for  the  lamps  in  order  to  avoid  varying  voltage  which 
is  apt  to  result  if  the  motors  are  connected  to  the  same  circuits 
with  the  lamps. 


MEZZANINE 

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ELEVATION 
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BENCH 

|BENCH_! 

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BENCH 

|BENCH  ; 

MEZZANINE 

FLOOR 


POWqR  UNIT' 


l^LOWPOWERTjNIT~5         ~° 


BENCHES^ 


PLAN 

FIG.  19.  This  shows  a  v  e  r  y 
poor  arrangement 
of  artificial  light- 
ing by  means  of 
large  lamps  mount- 
ed too  close  to  the 
floor.  Compare 
this  poor  lighting 
scheme  with  the 
improved  plan  in 
Fig.  20. 


ELEVATION 

40'-0"---. 

— » 


;  TBENCH: 

=0 

•csi         TBENCH 


PLAN 

FIG.  20.  This  illustration  is 
to  be  compared 
with  Fig.  19.  It 
Indicates  an  im- 
proved scheme  over 
that  shown  in 
Fig.  19  ;  made  pos- 
sible by  the  use  of 
smaller  lamps. 


51.  Constant  voltage.     In  addition  to  the  superior  illumina- 
tion  resulting  'from   lamps   supplied   from   constant   voltage 
mains,  some  types  operate  with  longer  life  or  very  much  better 
mechanically  when  supplied  with  constant  voltage  than  other- 
wise.    These  features  will  therefore  generally  more  than  offset 
the  somewhat  greater  cost  of  maintaining  separate  circuits  for 
each  class  of  service.     In  like  manner  and  for  similar  reasons, 
it  is  advisable  to  place  gas  lamps  on  supply  lines  separate  from 
those  delivering  gas  for  power  purposes. 

CONTROL  OF  LAMPS  AND  ARRANGEMENT  OF  SWITCHES. 

52.  The  control  of  lamps  in  factory  and  mill  lighting  is 
important  in  all  cases,  but  specially  so  where  a  large  number 
of  lamps  is  used  in  preference  to  a  small  number  for  a  given 


46 


GENERAL   LIGHTING   SAFETY   ORDERS. 


J      ^ 

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Fia.  22. 


Pi.AN 
Fio.  23. 


These  three  illustrations  show  various  ways  in  which  a  factory  space  of  16  ft. 
girder  clearance  can  be  handled,  depending  on  the  class  of  work  performed. 
The  first  case,  Fig.  21,  is  fairly  satisfactory  for  storage  spaces,  and  either 
the  second  or  third  cases,  Figs.  22  or  23,  can  be  employed  for  bench  assembly 
or  manufacturing.  The  third  case,  Fig.  23,  is  to  be  preferred  where  the 
class  of  work  consists  of  the  handling  of  small  machinery  parts. 


GENERAL   LIGHTING   SAFETY   ORDERS.  47 

floor  area.  For  example,  where  an  overhead  system  of  tung- 
sten lamps  of  small  size  is  used,  a  large  number  will,  of  course, 
be  necessary  for  a  given  floor  area,  and  in  such  cases  the 
number  of  control  circuits  may  at  times  seem  excessive  when 
planned  out  for  sufficient  flexibility  of  operation.  Such  cir- 
cuits, however,  in  rendering  the  system  more  flexible,  will  be 
more  than  paid  for  by  the  saving  in  energy  and  maintenance 
due  to  the  turning  out  of  lamps  not  needed  in  certain  sections 
of  the  factory  or  mill,  provided  the  number  of  hours  per  day 
during  which  the  lamps  are  used  on  the  average  is  relatively 
large,  and  the  differences  in  daylight  intensities  over  the  floor 
area  is  also  relatively  large. 

53.  Control  parallel  to  windows.     The  lamps  most  distant 
from  the  windows  will  usually  be  required  at  times  when  the 
natural  light  near  the  windows  is   entirely  adequate,  thus 
making  it  an  advantage  to  arrange  the  groups  of  lamps  in 
circuits   parallel   to   the   windows.     The   advantages   of   this 
method  are  further  apparent  when  it  is  considered  that  if  the 
lamps  are  controlled  in  rows  perpendicular  to  the  windows, 
all  lamps  in  a  row  will  necessarily  be  on  at  one  time,  while 
a  portion  only  may  be  required. 

54.  Practical  case.     The  foregoing  statement  may  be  devel- 
oped into  a  definite  proposition.     Thus,  to  install  a  single 
switch  may  involve  say  $5.00  as  its  first  cost.     If  ten  lamps  are 
to  be  controlled  from  a  single  switch,  these  ten  lamps  must 
obviously  either  all  be  turned  off  at  a  time  or  all  turned  on 
at  a  time.    An  additional  switch  at  a  cost  of  $5.00  will  permit 
either  half  of  these  ten  lamps  being  turned  off,  if  not  required 
at  certain  times  when  the  remaining  five  are  needed.     This 
extra  switch  may  or  may  not  be  an  economy.     Consider,  for 
example,  the  case  where  these  five  lamps  are  of  the  60-watt 
tungsten  type,  and  that  they  are  turned  off  by  the  extra  switch 
on  an  average  of  one-half  an  hour  per  day  while  the  others  are 
needed,  or  vice  versa.     In  a  year's  time,  the  energy  saved  at 
1  cent  per  kilowatt-hour,  will  amount  to  perhaps  50  cents. 
At  this  rate  it  will  require  ten  years  for  the  energy  saved  to 
pay  for  the  first  cost  of  the  extra  switch.     This  would  not  be 
considered  a  distinct  economy.     If,  however,  the  energy  cost 
be  greater,  and  more  nearly  the  average  under  actual  con- 
ditions, or  if  the  number  of  hours  per  day  during  which  a 


48  GENERAL   LIGHTING   SAFETY   ORDERS. 

portion  only  of  the  lamps  will  not  be  used,  be  greater,  then 
these  values  will  be  correspondingly  modified. 

55.  Locating  switch-es  and  controls.     In  locating  switches 
or  controls  in  factory  and  mill  aisles,  care  should  be  exercised 
to  arrange  them  systematically,  that  is,  on  columns  situated 
on  the  same  side  of  the  aisle  and  on  the  same  relative  side  of 
each  column.     This  plan  materially  simplifies  the  finding  of 
switches  or  controls,  by  those  responsible  for  turning  on  and 
off  the  lamps,  and  is  particularly  important  where  a  given 
floor  space  is  illuminated  by  a  large  number  of  small  or  medium 
sized  lamps  distributed  uniformly  over  the  ceiling  area,  a  fea- 
ture which  is  usually  accompanied  by  the  use  of  a  relatively 
large  number  of  switches  or  controls. 

SYSTEMATIC      PROCEDURE      SHOULD      BE      FOLLOWED      IN 

CHANGING   A   POOR    LIGHTING   SYSTEM    OVER  TO  AN 

IMPROVED  ARRANGEMENT. 

56.  When  undertaking  the  change  from  an  old  to  a  new 
lighting  system,  the  various  forms  of  illumination  which  are 
adapted  to  factory  and  mill  spaces  should  be  studied,  and  an 
investigation  made  of  the  various  types  of  gas  and  electric 
lamps  on  the  market  which  are  available  for  the  purpose. 

57.  Time  should  be  allowed  for  a  study  of  the  given  locations 
to  be  lighted;  for  preparing  the  plans  of  procedure  in  the 
installation  of  the  gas  or  electric  lamps  and  auxiliaries;  and 
for  customary  delays  in  the  receipt  of  the  necessary  supplies 
and  accessories  to  the  work  in  hand.     Altogether,  therefore, 
work  of  this  kind  requires  considerable  time  for  its  completion. 

58.  Using  the  shop  force.     In  large  factories  or  mills,   a 
wiring  or  gas-fitting  force  is  sometimes  a  part  of  the  mainte- 
nance division.     The  work  of  the  wiremen  or  fitters  is  likely 
to  be  heaviest  in  the  winter,  due  to  the  dark  days.     Where 
this  condition  exists,  there  is  all  the  more  reason  to  apportion 
out  new  work  so  as  to  accomplish  it  during  the  months  of  least 
wiring  and  piping  repair  activity,  and  further,  at  that  time 
of  the  year  when  employees  will  be  comparatively  unaffected 
by  the  disturbances  usually  associated  with  a  change  from  an 
old  to  a  new  lighting  system  through  possible  irregularities 
in  the  illumination  service  while  the  wiremen  or  fitters  are 
at  work. 


GENERAL   LIGHTING   SAFETY   ORDERS.  49 

59.  Distribution    of    expense.     Another    feature    different 
from  the  foregoing  viewpoint  is  in  the  distribution  of  the 
installation    cost    over    a    relatively    long    interval.     If,    for 
example,  the  system  is  desired  for  the  approaching  winter,  the 
complete  wiring  or  piping  plans  may  be  drawn  up  and  blocked 
out  into  three,  four  or  even  more  sections,  thus  spreading  the 
expense  over  as  many  months. 

60.  Yearly  appropriation.     In  some  shops  a  given  appro- 
priation may  be  allotted  each  year  for  building  equipment. 
From  the  standpoint  of  finance  plans,  it  may  thus  be  desirable 
to  distribute  outlays  of  this  nature  over  the  year,  rather  than 
to  concentrate  them  at  any  one  time.     An  important  consid- 
eration  in   this  method  of  installing  lamps,  however,   is  to 
prepare  in  as  far  as  possible  the  complete  plans  in  advance, 
at  least  as  regards  given  factory  or  mill  sections,  so  as  to  insure 
a  uniform  and  symmetrical  installation  as  a  whole  when  the 
component  parts  are  finished. 

REFLECTORS    AND    THEIR    EFFECT    ON    EFFICIENCY. 

61.  A  reflector  or  shade  is  used  in  conjunction  with  a  lamp 
for  the  purpose  of  reducing  the  glare  otherwise  caused  by 
looking  directly  into  the  bare  lamp,  as  well  as  for  the  purpose 
of  redirecting  the  light  most  effectively  to  the  work. 

62.  Reflectors  and  shades,  both  metal  and  glass,  are  now 
obtainable  for  each  size  of  incandescent  electric  and  gas  lamp. 
For  a  certain  ratio  between  the  spacing  and  the  height  of  the 
lamps,  a  reflector  can  nearly  always  be  selected  which  will 
furnish  uniform  illumination  over  the  working  surface. 

63.  Function  of  reflector.     Owing  to  the  direction  of  the 
light  from  the  lamp,  nearly  all  types  of  lamps,  in  addition 
to  the  downward  light,  furnish  some  rays  which  go  upwards 
and  away  in  other  directions  from  the  objects  to  be  illumi- 
nated, and  are  therefore  relatively  not  useful.     Furthermore, 
a  bright  source  in  the  field  of  vision  causes  an  involuntary 
contraction  of  the  pupil  of  the  eye,  which  is  equivalent  to  a 
decrease  in  illumination  in  so  far  as  the  eye  is  concerned. 
Hence,  while  reflectors  or  shades  may  at  first  seem  to  reduce 
the  amount  of  light  in  the  upper  part  of  the  room,  their  use 
actually  increases  the  amount  of  light  in  a  downward  useful 
direction,  and  improves  the  "seeing,"  due  to  the  better  con- 
ditions which  surround  the  eyes.     The  economic  function  of 


50  GENERAL   LIGHTING   SAFETY   ORDERS. 

the  reflector  as  contrasted  to  this  easier  condition  it  affords 
the  eyes,  is  to  intercept  the  otherwise  useless  or  comparatively 
useless  rays  which  do  not  ordinarily  reach  the  work,  and  to 
reflect  them  in  a  useful  direction.  In  performing  this  func- 
tion, there  is  a  choice  through  the  design  of  the  reflector,  in 
the  manner  of  distributing  the  light,  so  as  to  make  the  illu- 
mination on  the  floor  space  uniform  with  certain  spacing 
distances  and  mounting  heights  as  previously  mentioned. 

64.  Avoiding  dark  spots.     With  the  use  of  lamps  for  which 
a  large  variety  of  reflectors  is  available,  the  proper  reflector 
should  therefore  be  chosen  so  as  to  give  the  desired  distribu- 
tion of  light.     In  other  cases,  as  in  the  use  of  the  gas  or  electric 
arc  lamps,  where  the  globe  or  reflector  is  usually  a  fixed  part 
of  the  lamp,  care  must  be  exercised  to  space  the  lamps  at 
sufficiently  close  intervals  to  insure  uniformity  of  the  illumi- 
nation, that  is,   a  freedom  from  the  relatively  dark  spaces 
which  exist  between  lamps  when  spaced  too  far  apart. 

65.  Light  interiors.     With  a  light  ceiling,  the  reflection  of 
that  part  of  the  light  which  passes  through  a  glass  reflector 
to  the  ceiling,  and  which  is  added  to  the  light  thrown  down- 
ward from  the  under  surface  of  the  reflector,  is  a  factor  in 
building  up  the  intensity  of  the  illumination  on  the  working 
surface.     Great    importance    is    therefore    attached    to    light 
interior  colors,  especially  on  ceilings  and  the  upper  portions 
of  walls,  both  in  reinforcing  the  direct  illumination,  and  in 
giving  diffusion,  which  in  turn  adds  to  the  amount  of  light 
received  on  the  side  of  a  piece  of  work.     It  should  also  be 
stated  that  the   intensity   of  the   light  from   bare   overhead 
lamps  when  measured  on  the  working  surface  may  be  increased 
by  as  much  as  60  per  cent  through  the  use  of  efficient  reflectors. 
This  is  due  to  the  utilization  of  the  horizontal  rays  of  light 
as  previously  stated,  which  predominate  in  the  bare  lamp, 
whereas  the  most  effective  light  in  factory  and  mill  work  is 
apt  to  be  that  which  is  directed  downward. 

66.  Points  to  consider.     Reflectors  will  not  be  classified  here 
from  the  commercial  standpoint,  but  the  following  items  should 
be  given  consideration  in  the  selection  of  the  type  of  reflector 
for  factory  or  mill  use : 

1.  Utilization  efficiency.     How  much  does  the  reflector 
contribute  to  the  effective  illumination  on  the  work? 

2.  The  effect  in  reducing  glare. 


GENERAL   LIGHTING   SAFETY   ORDERS.  51 

3.  Natural  deterioration  with  age  through  accumula- 
.  tions  of  dust  and  dirt. 

4.  Ease  in  handling  and  uniformity  of  manufacture. 

5.  Physical  strength   and   the   absence   of   projections 
which  may  increase  the  breakage  in  case  of  glass  reflectors. 

67.  A  study  of  the  various  reflectors  on  the  market  with  the 
aid  of  these  items  as  a  basis  will  determine  what  reflectors  are 
best  adapted  to  given  conditions.     Regarding  the  third  item 
in  the  foregoing  list,  it  may  be  stated  that  under  comparative 
tests  in  service,  the  accumulations  of  dust  and  dirt  on  glass 
reflectors  do  not  seem  to  be  any  greater  than  the  coating  of 
dirt  which  accumulates  on  the  inside  of  a  metal  reflector  in 
the  same  length  of  time. 

SIDE    LIGHT    IMPORTANT    IN    SOME    FACTORY    AND    MILL 
OPERATIONS. 

68.  It  has  been  customary  in  many  cases  to  measure  the 
effectiveness  of  illumination  in  terms  of  the  vertically  down- 
ward component  of  the  light.     This  method  has  ignored  the 
value  of  side  components  in  relation  to  vertical  surfaces  and 
openings   in   the   side   of   the   work.     It   is   sometimes   more 
necessary  to  light  the  side  of  the  machine  or  the  side  of  a 
piece  of  work  than  the  horizontal  surface.     If,  then,  in  design- 
ing a  factory  or  mill  lighting  system,  the  prime  object  is  the 
production  of  the  greatest  amount  of  downward  illumination, 
it  may  happen  that  the  side  component  is  so  small  that  the 
sides  of  machinery  or  of  work  are  inadequately  lighted. 

69.  Two  ways  to  secure  side  lights.     Experience  indicates 
that  there  are  two  general  ways  in  which  to  secure  adequate 
side  lighting.     One  of  these  methods  is  to  lower  the  lamps, 
and  the  other  is  to  use  broader  distributing  reflectors  than  are 
called  for  by  the  rules  which  consider  uniformity  of  the  down- 
ward illumination  only.     Side  walls  or  other  reflecting  surfaces 
will  modify  the  results.      Thus,  after  the  determination  of  a  cer- 
tain type  of  reflector  for  producing  uniform  vertically  down- 
ward illumination,  it  may  be  found  that  more  side  light  is 
necessary,    and   this   extra   side    component    may,    as   stated, 
usually  be  secured  by  selecting  a  somewhat  more  distributing 
reflector.     Broader  distributing  reflectors  are  apt  to  result  in 
less  downward  illumination  and  will  sometimes  call  for  larger 
lamps  than  found  necessary  by  preliminary  calculations. 


52  GENERAL  LIGHTING   SAFETY   ORDERS. 

70.  Practical  case.     As  an  illustration,  in  a  certain  lighting 
system  a  vertically  downward  intensity  of  about  3  foot-candles 
was  deemed  sufficient  for  the  work  involved.     Measurements 
and  observations  showed  that  the  side  light  was  insufficient. 
In  this  particular  installation  it  was  found  necessary  to  pro- 
duce a  vertically  downward  intensity  of  about  5  foot-candles 
on  the  average  in  order  to  secure  an  intensity  of  about  2  foot- 
candles  on  the  side  of  the  work,  and  also  to  use  a  somewhat 
broader  distributing  reflector  than  at  first  chosen.     Two  foot- 
candles  on  the  sides  of  the  work  were  sufficient  in  this  case 
where  bench  work  and  work  in  the  vise  on  small  machine  parts 
were  conducted. 

71.  Keeping  the  lamps  high.     It  is  recommended  that  the 
lamps  be  mounted  near  the  ceiling  in   all  reasonable  cases 
where  side   light   is   necessary,    and  that   the   side   light   be 
increased,  not  by  lowering  the  lamps,  but  through  the  medium 
of  broader  distributing  reflectors  and  larger  lamps,  if  required. 
This  attitude  is  taken  on  account  of  the  glare  which  results 
when  lamps  are  mounted  too  close  to  the  work,  a  feature  most 
noticeable  in  the  absence  of  a  reflector  or  where  glass  reflectors 
are  used. 

72.  Maintenance.     Provision  should  be  made  for  systematic 
upkeep  of  natural  and  artificial  lighting. 

73.  Windows.     Factory  and  mill  windows  become  covered 
in  time  with  dirt,  and  produce  greatly  decreased  values  of 
natural  light  in  consequence.     These  losses  may  easily  be  great 
enough  to  affect  the  workmen  seriously,  and  to  necessitate  the 
use  of  artificial  light  at  times  when  otherwise  it  would  not  be 
required.     Dark  surroundings  also  increase  the  likelihood  of 
accidents.     Regular  window  cleaning  should  therefore  be  a 
part  of  the  routine  of  every  factory  and  mill  building  or  group 
of  buildings. 

74.  Lamps.     Carbon   filament,    mercury-vapor,   gas   mantle 
and  tungsten  lamps  burn  out  or  break,  globes  and  reflectors 
become  soiled,  and  the  various  other  items  of  deterioration 
take  place  so  gradually  that  in  many  cases  they  are  given  no 
special  concern  in  the  practical  economy  of  the  shop.     More- 
over, it  is  hardly  necessary  to  mention  the  fact  that  often 
lighting  systems  are  allowed  to  deteriorate  to  an  extreme  point 
and  nothing  is  done  unless  complaints  come  in  from  employees 


GENERAL   LIGHTING   SAFETY   ORDERS. 


53 


after  the  lighting  facilities  here  and  there  throughout  the  shop 
have  become  so  poor  that  work  has  to  be  discontinued  tempo- 
rarily. The  losses  of  time  from  such  circumstances,  when 
added  up  throughout  a  year,  are  more  than  likely  to  exceed 
the  expense  of  systematic  attention  to  such  maintenance  items 
in  advance. 

75.  Overhead  system.     Furthermore,  with  modern  methods 
where  the  lamps  are  usually  mounted  overhead  rather  than 
close  to  each  machine,  the  importance  of  relieving  the  workmen 
from  any  care  of  the  lamps,  and  placing  it  in  the  hands  of  a 
maintenance  department  is  even  greater  than  has  been  the 
case  in  the  past,  particularly  in  large  plants. 

76.  Reflector  cleaning.     The  serious  loss  of  light  when  globes 
and   reflectors   are   allowed  to   go   for   long  periods  without 
cleaning  is  shown  in  Fig.  25.     This  set  of  curves  resulted  from 
a  test  on  a  glass  reflector  used  with  a  tungsten  lamp.     The  one 
curve  shows  the  value  of  the  light  given  by  the  lamp  at  dif- 
ferent angles  when  the  lamp  and  reflector  are  clean,  while  the 
smaller  curve  shows  the  enormous  reduction  of  light  after  the 
lamp  and  reflector  have  been  in  service  for  about  four  months 
without  being  cleaned. 


30° 
FIG.  25. 


15" 


30- 


Curves  showing  serious 
losses  of  light  from  a 
tungsten  lamp  and  its 
reflector,  due  to  accumu- 
lations of  dirt.  This  is 
a  condition  applicable 
to  all  types  of  lamps,  as 
other  illuminants  suffer 
corresponding  losses 
from  dirt  accumula- 
tions. 


77.  In  this  particular  case,  which  is  a  typical  one,  the  loss 
of  light  at  the  end  of  the  four-month  interval  amounted  to 
about  50  per  cent.  The  cost  of  electrical  energy  in  this  shop 


54 


GENERAL   LIGHTING   SAFETY   ORDERS. 


FIG.  26.  Very  poor  lighting  in  a  worsted  goods  factory.  The  wiring  is  badly 
arranged,  the  contrasts  between  light  and  dark  portions  of  the 
room  are  excessive,  and  in  some  cases  the  wrong  size  of  lamp  is 
used  in  a  given  reflector.  The  system  is  unsightly  and  represents 
bad  practice.  Compare  with  Fiff.  27. 


FIG.  27.  Worsted  mill  with  localized  general  illumination.  This  is  an  exam- 
ple of  excellent  illumination  with  tungsten  and  metal  reflectors. 
Note  the  reflection  from  the  goods  to  their  ceiling.  Compare  with 
Fiff.  26. 


GENERAL   LIGHTING   SAFETY   ORDERS. 


55 


FIG.  28.  Very  poor  arrangement  of  arc  lamps.  The  lamps  are  mounted  to 
one  side  of  aisle  over  line  shafting.  Very  little  light  reaches  the 
machinery  to  the  right.  Compare  with  Fig.  29. 


FIG.  29.     Well  planned  system  of  arc  lighting.     The  lamps  are  high  and  above 
the  ordinary  line  of  vision.     Compare  with  Fig.  28. 


56  GENERAL   LIGHTING   SAFETY   ORDERS. 

was  such  that  the  loss  of  light  during  the  fourth  month 
amounted  to  about  12  cents,  while  the  total  cost  of  taking 
down,  washing  and  replacing  this  reflector  amounted  to 
about  3  cents.  The  economy  of  a  fairly  frequent  attention  to 
cleaning  of  such  reflectors  is  at  once  apparent,  even  if  the 
improved  condition  of  the  light  in  itself  be  ignored. 

78.  The  example  just  given  will  serve  to  illustrate  the  class 
of  upkeep  problems  which  are  involved  in  shop  lighting.     The 
most  forcible  emphasis  is  applicable  to  the  idea  that  system 
may  properly  be  called  a  first  step  towards  success  in  this  line 
of  maintenance  work. 

79.  A  method  of  inspection  and  maintenance.     In  one  large 
factory    a    regularly    developed    method    of    inspection    and 
renewals  is  employed.     As  an  example,  the  method  as  applied 
to  several  thousand  tungsten  lamps  which  are  in  service  in 
the  various  buildings  will  be  described.     All  the  lamps  are 
inspected  once   per   day,    except   Saturday   and   Sunday.     A 
regular  route  is  followed  by  the  inspector,  and  all  burned  out 
lamps,  broken  switches,  loose  fuses,  and  similar  items  are  noted. 
Careful  observation  is  also  made  of  reflectors  which  appear 
to  need  washing  and  any  other  points  which  might  affect  the 
efficiency  of  the  system,  after  which  a  report  is  made  up  about 
noon  and  promptly  sent  to  the  maintenance  department  to 
permit  all  renewals  and  repairs  to  be  made  before  night.     In 
this  manner  the  lamps  are  well  maintained  from  day  to  day. 

80.  Marking  columns.     To  facilitate  this  renewal  work,  it 
has  been  found  advantageous  to  mark  all  columns  through  this 
shop.     The  inspector  is  thus  enabled  to  indicate  clearly  the 
location  of  each  burned  out  lamp  and  the  renewal  man  to 
locate  it  without  delay.     It  is  helpful  now  and  then  in  like 
manner  to   have   the  inspector  note   the   unnecessary   lamps 
found  burning  when  artificial  light  is  not  required.     If  lamps 
are  found  burning  at  such  times,  a  note  sent  to  the  head  of 
the   department   calling   attention   to   the   matter,   is   usually 
sufficient  to  remedy  the  difficulty. 

81.  Noting    soiled    reflectors.     As    a    check    on    a    regular 
cleaning  schedule  the  inspector  should  note  all  reflectors  in 
need  of  cleaning.     The  frequency  of  each  cleaning  will  depend 
on  the  rate  of  deterioration  due  to  the  settlement  of  dirt  on 
the  surface  of  the  glass  or  metal  and  also  on  the  surface  of 


GENERAL   LIGHTING   SAFETY   ORDERS.  57 

lamps,  and  the  fact  should  be  kept  in  mind  that  the  amount 
of  dirt  on  a  reflector  is  nearly  always  deceptive,  that  is, 
reflectors  which  have  suffered  a  large  deterioration  in  efficiency 
clue  to  dirt  often  appear  fairly  clean,  and  for  this  reason  it  is 
best  to  increase  the  frequency  of  cleaning  somewhat  over  that 
which  seems  sufficient  from  observation,  particularly  in  view 
of  the  fact  that  tests  indicate  large  reductions  of  light  from 
apparently  small  accumulations  of  dust  and  dirt. 

82.  A  method  of  washing.     In  the  factory  just  referred  to, 
all  reflectors  are  removed  to  a  central  washing  point.     Where 
the  number  of  reflectors  to  be  hauled  is  large,  a  truck  is  used. 
Often,  however,  where  only  a  small  number  of  reflectors  is  to 
be  transported,  small  hand  racks,  devised  for  the  purpose,  are 
employed.     When  an  installation  is  in  need  of  washing,  the 
scheme  is  to  haul  sufficient  clean  reflectors  to  the  location  in 
question.     The  soiled  reflectors  are  then  taken  down  and  clean 
ones  immediately  put  into  place,  after  which  the  soiled  reflec- 
tors are  removed  to  the  central  washing  point,  washed  and 
put  into  stock  for  the  next  location. 

EXPERT  ASSISTANCE  SUGGESTED. 

83.  The  advantages  of  securing  expert  assistance  in  dealing 
with  illumination  are  strongly  emphasized.     The  points  which 
come  up  for  solution  are  complex  and  require,  in  many  cases, 
the  judgment  of  one  who  has  had  wide  experience  in  the 
lighting  field. 

OTHER   FEATURES  OF   EYE   PROTECTION. 

84.  Care  is  urged  on  the  part  of  those  responsible  for  the 
health  and  welfare  of  employees  to  see  that  adequate  eye  pro- 
tection is  afforded  in  all  operations  which  are  apt  to  cause 
injury  to  eyesight  if  such  protection  is  neglected.     As  typical 
of  such  other  causes  of  danger  to  eyesight,  arc  welding  may 
be  mentioned,  where  the  operator,  according  to  accepted  prac- 
tice, must  wear  a  helmet  in  general.     Protective  glasses  for  this 
purpose  should  not  be  judged  as  to  their  protective  properties 
by  mere  visual  inspection.     They  should,  therefore,  be  analyzed 
for  their  spectral  transmission  of  invisible   radiation.     Pro- 
tective measures  should  also  be  taken  to  prevent  onlookers 
from  being  unduly  exposed  to  such  eye  dangers,  by  enclosing 


58  GENERAL   LIGHTING   SAFETY    ORDERS. 

the  welding  operations  with  suitable  partitions.  These  gen- 
eral remarks  apply  with  equal  force  from  the  standpoint  of 
those  handling  the  operations  to  such  other  cases  as  the  testing 
of  arc  lamps,  inspection  of  hot  metal  and  similar  cases. 

GOOD  AND  BAD  LIGHTING  COMPARED. 

85.  In  order  to  give  an  idea   of  good  and  bad  lighting, 
Figs.  13,  14,  26,  27,  28  and  29  are  shown.     These  illustrations 
indicate  the  use  of  various  types  of  lamps  and  a  reference  to 
the  captions  under  the  illustrations  will  bring  out  the  weak 
points  of  the  poorly  lighted  spaces,  as  well  as  the  points  of 
excellence  in  those  cases  which  are  designed  in  conformity 
with  good  illumination  practice. 

METHOD  OF  MEASURING  SURFACE  BRIGHTNESS. 

86.  The  candlepower  of  the  brightest  square  inch  of  light 
source  may  be  measured  by  means  of  a  portable  photometer. 
An  opaque  board  with  a  square  or  circle  hole  one-quarter  square 
inch  in  area  is  placed  against  the  surface  of  the  light  source 
in  such  a  position  that  the  brightest  spot  emits  light  through 
the  hole  in  the  board.     The  board  must  be  of  such  size  as  to 
prevent  any  other  light  from  the  source  to  strike  the  photo- 
meter.    The  photometer  is  placed  at  some  convenient  distance 
from  the  light  source   unit,   and  read,   care  being  taken  to 
exclude   all   light   from   the  photometer  except  that  coming 
through  the  hole.     If  the  photometer  is  read  at  a  distance  of 
one  foot  from  the  light  source,  the  foot-candles  observed  multi- 
plied by  four  will  be  the  candlepower;  if  the  photometer  is 
two    feet    distant    from    the    light    source,    the    foot-candles 
observed  must  be  multiplied  by  sixteen  to  obtain  the  candle- 
power;  if  three  feet,  they  must  be  multiplied  by  thirty-six, 
etc.,  the  observed  foot-candles  in  all  cases  being  multiplied 
by  the  square  of  the  distance  times  four  between  the  light 
source  and  the  photometer,  when  the  readings  were  taken  to 
obtain  the  candlepower  of  the  source. 


INDEX. 


A  Sub- 
Page         Order    division 

Accessories 7-8          1507 

Aisles: 

Minimum  intensity  (foot-candles) 5          1503           2 

Workspace,  emergency  lighting  of 8          1508           a 

Appendix 10-58 

Control  of  lamps  and  arrangement  of  switches.  45-48 

Daylight    22-28 

Effects  on  factory  and  mill  lighting  produced  by 

modern  lamps 31-32 

Expert  assistance  suggested 57 

General  information  and  suggestions 10-11 

General  requirements  of  artificial  lighting 32-33 

Good  and  bad  lighting  compared 58 

Lighting  circuits  for  electric  lamps  and  supply 

mains  for  gas  lamps 44-45 

Method  of  measuring  surface  brightness 58 

Minimum  and  desirable  illumination 11 

Old  and  new  lamps 

Other  features  of  eye  protection 57 

Overhead    and    specific    methods    of    artificial 

lighting    _" 33-34 

Reflectors  and  their  effect  on  efficiency 49-51 

Side  light  important  in  some  factory  and  mill 

operations    51—57 

Systematic    procedure    should    be    followed    in 

changing  a  poor  lighting  system  over  to  an 

improved  arrangement 48-49 

Table   of  recommended   intensities   for   detailed 

operations  and  processes 12-22 

Value  of  adequate  illumination 28-31 

Various  locations  illustrated 34-44 

Artificial   light   5-6          1503 

Artificial  light  required 5          1501 

Awnings,  shades,  diffusive  or  refractive  glass 5         1502           b 

B 

Brightness : 

Definition  of 4         1500           h 

Sky    5          1502           a 

C 

Candle,  definition  of 4          1500           a 

Candlepower,   definition   of 4          1500           a 

Coarse  work,  minimum  intensity  (foot-candles) 6         1503            4 

Committee  on  General  Lighting  Safety  Orders 3 

Control  of  emergency  lighting 8-9          1508           d 

Control  and  switching  apparatus,  installation 9          1509           a 

Control    and    switching    apparatus    on    emergency, 

identification   9          1509           b 

D 

Definitions 4-5          1500 

Brightness     4          1500           h 

Candle    4          1500           a 

Candlepower   4          1500           a 

Eyestrain    4          1500            j 

Foot-candle   4          1500           c 

Foot-candles  at  floor-level 5          1500           o 

Foot-candles  at  the  work 5          1500           n 


60 


INDEX. 


D — Continued. 

Definitions — Continued. 

Glare     ___J 

Illumination    

Intensity  of  illumination 

Lamp    

Lamps,  local 

Lamps,  overhead 

Local  lamps 

Lumen 

Overhead  lamps 

Photometer    

Shaded 

Detail,  discrimination  of,  minimum  intensity    (foot- 
candles)    

Diagram  illustrating  shading  of  lamps  for  overhead 

lighting 

Diffusive  window  glass 

Distribution  of  illumination  uniform 

Distribution  of  light  on  work 

Drafting,  minimum  intensity  (foot-candles) 

Dressing  rooms,  minimum  intensity  ( foot-candles  )__ 


Elevator  cars,  minimum  intensity   (foot-candles) 

Elevator  entrances,  minimum  intensity  (foot- 
candles)  

Emergency  lighting 

Controlling  equipment 

Exits  

Hospitals  

Installation  of 

Intensity  of  (minimum) 

Moving  picture  exhibition  places 

Outside  landings  of  fire  escapes 

Passageways  

Public  meeting  halls 

Schools 

Source  of  supply 

Stairways  

Supply  

Systems,  including  supply  and  branch  lines 

Systems,  independent  source 

Theaters  

Workspace  aisles 

Engraving,  minimum  intensity   (foot-candles) 


Exits: 

Emergency  lighting  of 

Minimum  intensity  (foot-candles). 

Eyestrain 

Definition  of  _ 


Fine     manufacturing,      minimum     intensity      (foot- 
candles)     

Foot-candle,  definition  of 

Foot-candles  at  floor  level,  definition  of 

Foot-candles  at  the  work,  definition  of 


General  requirements 

Glare,   definition   of 

Glass  window,  diffusive  and  refractive. 


Sub- 

Order 

division 

1500 

i 

1500 

I 

1500 

m 

1500 

e 

1500 

f 

1500 

9 

1500 

f 

1500 

b 

1500 

9 

1500 

d 

1500 

7c 

1503 

4,  5,  6 

1505 

1502 

b 

1507 

1507 

1503 

8 

1503 

3 

1503 

3 

1503 

2 

1508 

1508 

d 

1508 

a 

1508 

d 

1508 

b 

1508 

c 

1508 

d 

1508 

a 

1508 

a 

1508 

d 

1508 

d 

1508 

d 

1508 

a 

1508 

d 

1508 

b 

1508 

b}d 

1508 

d 

1508 

a 

1503 

8 

1508 

a 

1503 

2 

1502 

b 

1500 

3 

1503 

7 

1500 

c 

1500 

o 

1500 

n 

1501 

1500 

1 

1502 

b 

INDEX. 
H 


61 


Sub- 
Halls     and     hallways,     minimum     intensity      (foot-  Page  Order    division 

candles)     5  1503           2 

Halls,  public  meeting,  emergency  lighting  of 8-9  1508           d 

Hospitals,  emergency  lighting  of 8-9  1508           d 

Identification  of  switching  and  control  apparatus  on 

emergency,  pilot  and  night  lights 9  1509           & 

Illumination  : 

Definition  of 4  1500            I 

Distribution  of 7-8  1507 

Emergency    8-9  1508 

Intensity    of,    definition 4  1500          m 

Intensity  (minimum)   of  emergency  lighting 8  1508            c 

Intensity  of  illumination,  definition  of 4  1500          m 

Intensities   (minimum)    5-6  1503 

Aisles    ! 5  1503           2 

Drafting    6  1503            8 

Dressing  rooms    5  1503           3 

Elevator  cars 5  1503 

Elevator   entrances   5  1503           2 

Engraving     6  1503            8 

Exits 5  1503           2 

Fine  manufacturing 6  1503           7 

Halls  and  hallways 5  1503 

Office  work 6  1503           7 

Passageways 5  1503           2 

Roadways   5  1503            1 

Rough    manufacturing   requiring   discrimination 

of  detail 6  1503           5 

Rough  manufacturing  requiring  closer  discrimi- 
nation  of   detail 6  1503           6 

Stairs     5  1503           2 

Stairways    5  1503 

Storage  spaces 5  1503 

Toilet   rooms 5  1503            3 

Wash  rooms 5  1503 

Water-closet  compartments 5  1503            3 

Watchmaking 6  1503            8 

Work  not  requiring  discrimination  of  detail 6  1503           4 

Yards    5  1503           1 

L 

Lamp,  definition  of 4  1500           e 

Lamps : 

Local,  definition  of 4  1500            / 

Local,    shading  of 7  1506 

Overhead,  definition  of 4  1500           g 

Overhead,  shading  of 6-7  1505 

Overhead,  shading  of,  diagram  illustrating 7  1505 

Landings  of  fire  escapes  (outside),  emergency  light- 
ing of 8  1508           a 

Light : 

Artificial    5-6  1503 

Distribution  on  work 7-8  1507 

Measurements    6  1504 

Required,  artificial  or  natural--.  5  1501 


62 


INDEX. 


L — Continued. 

Lighting :  ^ 

Emergency.     See  Emergency  Lighting.  Page  Order    division 

Local,   shading  of 7  1506 

Natural 5  1502 

Overhead,   shading  of 6-7  1505 

Roof   5  1502           a 

Skylights    5  1502           a 

Windows     5  1502           a 

Lights,  night  and  pilot: 

Identification    9  1509           & 

Installation  of 9  1509           a 

Local  lamps,  definition  of 4  1500            f 

Local  lighting,  shading  of  lamps  for 7  1506 

Lumen,  definition  of - 4  1500           6 

M 

Manufacturing,    minimum    intensity    (foot-candles)  : 

Fine    6  1503           7 

Rough    6  1503        5,  6 

Measurements    6  1504 

Minimum  intensities 5-6  1503 

Moving  picture  exhibition  places,  emergency  light- 
ing of 5  1502 

N 

Natural  lighting 5  1502 

Natural  light  required 5  1501 

Night  lights : 

Identification   9  1509           & 

Installation  of 9  1509           a 

O 

Office  work,  minimum  intensity   (foot-candles) 6  1503            7 

Outside  landings  of  fire  escapes,  emergency  light- 
ing of 8  1508  a 

Overhead  lamps,   definition  of 4  1500           g 

Overhead  lighting,  shading  of  lamps  for 6-7  1505 

Overhead  lighting,  shading  of  lamps  for,  diagram 

illustrating  7  1505 

Passageways :  P 

Emergency  lighting  of 8  1508           a 

Minimum  intensity   (foot-candles) 5  1503           2 

Photometer : 

Definition  of 4  1500           d 

Standardized    6  1504 

Pilot  lights: 

Identification   9  1509           & 

Installation  of 9  1509           a 

Public  meeting  halls,  emergency  lighting  of 8-9  1508           d 

R 

Reflectors   and  accessories 7—8  1507 

Refractive  window  glass 5  1502            & 

Requirements,  general 5  1501 

Roadways,  minimum  intensity   (foot-candles) 5  1503            I 

Roof-lighting 5  1502           a 

Rough  manufacturing,  minimum  intensity  (foot- 
candles)  6  1503  5,  6 


INDEX. 


63 


c 

Schools,  emergency  lighting  of  -------------------- 

Shaded,  definition  of  _____________________________ 

Shades   __________  1  _______________________________ 

Shading  of  lamps  for  local  lighting  ________________ 

Shading  of  lamps  for  overhead  lighting  ------------ 

Shading   of   lamps    for   overhead    lighting,    diagram 
illustrating  _______________________________ 

Skylight  lighting  ________________________________ 

Stairs,  minimum  intensity   (foot-candles)  __________ 

Stairways  : 

Emergency  lighting  of  ------------------------ 

Minimum  intensity   (foot-candles)  _____________ 

Storage  spaces,  minimum  intensity  (foot-candles)  __ 
Summary  of  safety  provisions  _____________________ 

Switches  or  controlling  apparatus,  installation  of  ___ 
Switching  and  control  apparatus  __________________ 

On  emergency   identification  ------------------ 


Page 

8-9 

4 

5 

7 

6-7 


Sub- 

Order  division 

1508  d 

1500  k 

1502  b 
1506 
1505 


7          1505 

5          1502  a 

5          1503  2 


8  1508 
5  1503 
5  1503 
3 

9  1509 
9  1509 
9  1509 


Theaters,  emergency  lighting  of  ___________________  8-9  1508           d 

Toilet  rooms,  minimum  intensity   (foot-candles)  ____  5  1503           3 

Traversed  spaces  ________________________________  5  1501 

W 

Wash  rooms,  minimum  intensity   (foot-candles)  ____  5  1503            3 

Watchmaking,  minimum  intensity  (foot-candles)  ___  6  1503           8 
Water-closet      compartments,      minimum      intensity 

(foot-candles)    ____________________________  5  1503            3 

Window  glass,  diffusive  and  refractive  _____________  5  1502           b 

Windows,  skylights  or  other  roof-lighting  construc- 

tion of  buildings  ___________________________  5  1502           a 

Work   of   coarse   nature,    minimum   intensity    (foot- 

candles)   ----------------------------------  6  1503            4 

Working  spaces  _________________________________  5  1501 

Workspace  aisles,   emergency  lighting  of  __________  8  1508           a 


Yards,  minimum  intensity    (foot-candles)  __________  5          1503 

APPENDIX.     For  table  of  contents  see  "Appendix"  listed  in  index. 


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